<html>

<head>
<meta http-equiv="Content-Language" content="en-us">
<meta name="GENERATOR" content="Microsoft FrontPage 5.0">
<meta name="ProgId" content="FrontPage.Editor.Document">
<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
<title>Filesystem Library for TR2</title>
</head>

<body>

  <table border="0" cellpadding="0" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="579">
    <tr>
      <td width="153" align="left" valign="top">Document number:</td>
      <td width="426">N3239 = 11-0009</td>
    </tr>
    <tr>
      <td width="153" align="left" valign="top">Date:</td>
      <td width="426">
      <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%Y-%m-%d" startspan -->2011-02-25<!--webbot bot="Timestamp" endspan i-checksum="12106" --></td>
    </tr>
    <tr>
      <td width="153" align="left" valign="top">Project:</td>
      <td width="426">Programming Language C++, Library Working Group</td>
    </tr>
    <tr>
      <td width="153" align="left" valign="top">Reply-to:</td>
      <td width="426">Beman Dawes &lt;bdawes at acm dot org&gt;</td>
    </tr>
  </table>


<h1>Filesystem Library Update for TR2 (Preliminary)</h1>


<p>This paper proposes that the&nbsp;filesystem library component of <i>C++ Standard 
Library Technical Report 2</i> be based on Version 3 of the Boost Filesystem 
Library (see <a href="http://www.boost.org/libs/filesystem">
www.boost.org/libs/filesystem</a>). Preliminary wording is provided. A
<a href="#TODO">TODO</a> list identifies remaining work to be done.</p>


<p><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1975.html">
J16/06-0045 = WG21/N1975</a>, Filesystem Library Proposal for TR2 (Revision 3), 
was adopted by the committee in April, 2006, at the Berlin meeting. Shortly 
afterward the Library Working Group set aside work on TR2 to concentrate on 
C++0x. In the meantime, work on the Boost version of the Filesystem Library has 
continued, and Version 3 of the library has been released. Changes include:</p>


  <ul>
    <li>A single class <code>path</code> handles all aspects of 
    internationalization, replacing the previous template and its <code>path</code> 
    and <code>wpath</code> instantiations. Character types <code>char</code>,
    <code>wchar_t</code>, <code>char16_t</code>, and <code>char32_t</code> are 
    supported. This is a major simplification of the path abstraction, 
    particularly for functions that take path arguments. This change was based 
    on a suggestion by Peter Dimov.<br>
&nbsp;</li>
    <li>Several operational functions have been added, including much better 
    symlink support, the ability to resize a file, and the ability to generate a 
    unique path.<br>
&nbsp;</li>
    <li>Support for error reporting via <code>error_code</code> is now uniform 
    throughout the operations functions.|<br>
&nbsp;</li>
    <li>Several functions have been renamed, based on feedback from users.</li>
  </ul>


<h2>Motivation and Scope</h2>


<p>The motivation and scope for a filesystem library were described in <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1975.html">
N1975</a>, and are not repeated here. A minor scope reduction is that an 
addition to the current C++ runtime library is no longer needed.</p>


<p>Boost Filesystem Version 3  introduced a single path type that interoperates well with both <code>
basic_string</code> and user defined string types. Thus the following Design 
alternatives paragraph is no long applicable:</p>


  <blockquote>


<p><strike><i>Single path type which can at runtime accept narrow or wide character 
pathnames.</i> Although certainly interesting, and possibly superior, such a 
design would not interoperate well with the current Standard Library's 
compile-time typed <code>basic_string</code>. A new runtime polymorphic string 
class would be the best place to experiment with this concept, not a path class.</strike></p>


  </blockquote>


  <h2><a name="TODO">TODO</a></h2>
  <ul>
    <li>Apply C++0X features. Boost.Filesystem needs to implement these to verify their 
    application is correct.</li>
    <li>Boost.Filesystem needs to implement <code>char16_t</code> and <code>char32_t</code> support to verify the 
    specification for these is correct.</li>
    <li>Class <code>file_status</code> is overdesigned. It holds just a single <code>file_type</code> variable, and that's unlikely to change 
  because of performance considerations. It would be simpler to eliminate class <code>
  file_status</code>, and just use <code>file_type</code> in its stead. Perhaps 
    rename to <code>file_status</code>. This hasn't been done in the Boost 
    because it would break existing code, albeit noisily.</li>
    <li>Replace path inserter and extractor <i>Effects</i> with prose, since the 
    current wording relies on 
  <code>boost::io::quoted</code></span>.</li>
    <li>Replace uses of <code>boost::iterator_facade</code>.</li>
    <li><code><a href="#Source">Source</a></code> is not specified as actually 
    implemented. Expose <code>path_traits</code>?</li>
    <li><i>Effects</i> for <code>copy</code> and <code>copy_directory</code> 
    need to be reviewed, revised, tested.</li>
  </ul>
  
<h2><a name="TOC">Table of Contents</a></h2>

<table border="0" cellpadding="0" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="100%">
  <tr>
    <td width="33%" valign="top">
    <p><a href="#Introduction">Introduction</a><br>
    <a href="#Definitions">Definitions</a><br>
    <a href="#Conformance">Conformance</a><br>
    <a href="#Header-filesystem-synopsis">
    Header &lt;filesystem&gt; synopsis</a><br>
    <a href="#Error-reporting">Error reporting</a><br>
    <a href="#class-path">Class path</a><br>
    &nbsp;&nbsp;&nbsp; <a href="#path-constructors">path constructors</a><br>
&nbsp;&nbsp;&nbsp; <a href="#path-assignments">path assignments</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-appends">path appends</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-modifiers">path modifiers</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-native-format-observers">path native 
    format observers</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-generic-format-observers">path generic 
    format observers</a><br>
&nbsp;&nbsp;&nbsp; <a href="#path-decomposition">path decomposition</a><br>
&nbsp;&nbsp;&nbsp; <a href="#path-query">path query</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-iterators">path iterators</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-deprecated-functions">path deprecated functions</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-non-member-functions">path non-member functions</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#path-inserter-extractor">path inserters and extractor</a>s<br>
</span> &nbsp;<a href="#Class-filesystem_error">Class filesystem_error</a><br>
&nbsp;&nbsp;&nbsp; <a href="#filesystem_error-members">filesystem_error 
    constructors</a><br>
&nbsp;&nbsp;&nbsp; f<a href="#filesystem_error-path1">ilesystem_error path1</a><br>
&nbsp;&nbsp;&nbsp; <a href="#filesystem_error-path2">filesystem_error path2</a><br>
&nbsp;&nbsp;&nbsp; <a href="#filesystem_error-what">filesystem_error what</a><br>
<a href="#Class-directory_entry">Class directory_entry</a><br>
&nbsp;&nbsp;&nbsp;
<a href="#directory_entry-constructors">directory_entry constructors</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#directory_entry-modifiers">directory_entry modifiers</a><br>
&nbsp;&nbsp;&nbsp;&nbsp;<a href="#directory_entry-observers">directory_entry observers</a><br>
<a href="#Class-directory_iterator">Class  directory_iterator</a><br>
&nbsp;&nbsp;&nbsp; <a href="#directory_iterator-members">directory_iterator 
    members</a><br>
<a href="#Class-recursive_directory_iterator">Class recursive_directory_iterator</a><br>
    <a href="#file_status">Class 
    file_status</a><br>
    &nbsp;</td>
    <td width="33%" valign="top">
    <p>
    <a href="#Operational-functions">
    Operational functions</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#absolute">absolute</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#copy">copy</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#copy_directory">copy_directory</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#copy_file">copy_file</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#copy_symlink">copy_symlink</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#create_directories">create_directories</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#create_directory">create_directory</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#create_hard_link">create_hard_link</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#create_symlink">create_symlink</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#current_path">current_path</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#exists">exists</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#equivalent">equivalent</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#file_size">file_size</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#hard_link_count">hard_link_count</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#initial_path">initial_path</a><br>
&nbsp;&nbsp;&nbsp;&nbsp  i<a href="#is_directory">s_directory</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#is_empty">is_empty</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#is_other">is_other</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#is_regular_file">is_regular_file</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#is_symlink">is_symlink</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#last_write_time">last_write_time</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#read_symlink">read_symlink</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#remove">remove</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#remove_all">remove_all</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#rename">rename</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#resize_file">resize_file</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#space">space</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#status">status</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#status_known">status_known</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#symlink_status">symlink_status</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#system_complete">system_complete</a><br>
&nbsp;&nbsp;&nbsp;&nbsp <a href="#temp_directory_path">temp_directory_path</a><br>
&nbsp;&nbsp;&nbsp;&nbsp; <a href="#unique_path">unique_path</a></td>
    <td width="34%" valign="top">
    <p>
    <a href="#File-streams">File streams</a><br>
<a href="#Path-decomposition-table">Path decomposition table</a><br>
<a href="#Acknowledgements">Acknowledgements</a><br>
<a href="#References">References</a><br>
&nbsp;</td>
  </tr>
</table>

  <h2>Proposed wording</h2>
  
  <p><span style="font-style: italic; background-color: rgb(224, 224, 224);">
  Gray-shaded italic text is commentary on the proposal. It is not to be added 
  to the TR.</span></p>
  
  <blockquote>
  <table border="1" cellpadding="7" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" bgcolor="#E0E0E0">
    <tr>
      <td><span style="font-style: italic; ">The 
      following wording is a lighted edited version of the Boost Filesystem 
      reference documentation. Although further editing is required, 
      the features described are relatively stable and major feature changes are not 
      anticipated. </span></td>
    </tr>
  </table>
  </blockquote>
  
  <p><span style="font-style: italic; background-color: #E0E0E0">Add the 
  following to the Technical Report's front 
  matter:</span></p>
  <p>The following standard contains provisions which, through reference in this 
  text, constitute provisions of this Technical Report. At the time of 
  publication, the editions indicated were valid. All standards are subject to 
  revision, and parties to agreements based on this Technical Report are 
  encouraged to investigate the possibility of applying the most recent editions 
  of the standard indicated below. Members of IEC and ISO maintain registers of 
  currently valid International Standards.</p>
  <ul>
    <li>ISO/IEC 9945:2003, <i>Portable Operating System Interface (POSIX<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1975.html#Footnote-1"><sup>1</sup></a>), 
    part 1 (Base Definitions) and part 2 (System Interfaces)</i>, both as 
    corrected by their respective 2004 Correction 1 documents.<p>[<i>Note:</i> 
    ISO/IEC 9945:2003 is also IEEE&nbsp;Std&nbsp;1003.1-2001, and The Open Group Base 
    Specifications, Issue 6, and is also known as The Single Unix<font face="Times New Roman"><sup><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1975.html#Footnote-2">2</a></sup><i><b>
    </b></i>Specification, Version 3. It is available from each of those 
    organizations, and may be read online or downloaded from
    <a href="http://www.unix.org/single_unix_specification/">
    www.unix.org/single_unix_specification/</a> <i>-- end note</i>]</font></li>
  </ul>
  <p>ISO/IEC 9945:2003, with the indicated corrections, is hereinafter called <i>
  POSIX</i>.</p>
  <p><a name="Footnote-1">Footnote 1</a>: <i>POSIX</i> is a registered 
  trademark of The IEEE.</p>
  <p><a name="Footnote-2">Footnote 2</a>: <i>UNIX</i> is a registered trademark 
  of The Open Group.</p>
  
  <p><span style="font-style: italic; background-color: #E0E0E0">Add the 
  following to the Technical Report as a new Clause:</span></p>

<h2>Filesystem Library</h2>

<p>This Clause describes components that  perform operations on file systems and 
their components, such as paths, regular files, 
and directories.</p>
<p>Operating systems such as <i>MAC OS, UNIX</i>, and <i>Windows</i> are mentioned 
in this Clause for purposes of illustration or to 
give guidance to implementers. No slight to other operating systems is implied 
or intended.</p>
<p><a name="Footnote-3">Footnote 3</a>: <i>MAC OS</i> is a registered trademark 
of Apple Inc.</p>
<p><a name="Footnote-4">Footnote 4</a>: <i>Windows</i> is a registered 
trademark of Microsoft Corporation.</p>
<h2><a name="Conformance">Conformance</a></h2>
  <p>Some library behavior is specified in this Clause by reference to
  <i>POSIX</i>. How such behavior is actually implemented is unspecified.</p>
  <blockquote>
    <p>[<i>Note:</i> This constitutes an &quot;as if&quot; rule for implementation of 
    operating system dependent behavior. Presumably implementations will call 
    native operating system API's, but this is not required. <i>--end note</i>]</p>
  </blockquote>
  <p>Implementations are encouraged, but not required, to support such behavior 
  as it is defined by <i>POSIX</i>. Implementations shall document behavior 
  that differs from the <i>POSIX</i> defined behavior. Implementations that do 
  not support exact <i>POSIX</i> behavior are encouraged to provide behavior as 
  close to <i>POSIX</i> behavior as is reasonable given the limitations of 
  actual operating systems and file systems. A diagnostic is required if an implementation cannot provide 
  reasonable behavior.</p>
<p>The behavior of functions described in this 
Clause 
may not be achieved in 
the presence of <a href="#Race-condition">race conditions</a>. No diagnostic is required.</p>
<p>If the possibility of race conditions would make it unreliable for a program to 
test for a precondition before calling a function described in this clause, the 
precondition is not specified in the function's <i>
Requires</i> element.</p>
<h2><a name="Definitions">Definitions</a></h2>
<p><i><b><a name="File">File</a></b><br>
</i>An object that can be written to, or read from, or both. A file 
has certain attributes, including type. Common types of files include regular files 
and directories. Other types of files, such as symbolic links, may be supported by the 
implementation.</p>
<p><b><i><a name="File-system">File system</a></i></b><br>
A collection of files and certain of their attributes.</p>
<p><b><i><a name="Filename">Filename</a></i></b><br>
The name of a file. Slash and 0x00 
characters are not permitted. Implementations may define additional 
characters or specific names that are not permitted. Filenames <code>.</code>&nbsp; 
and <code>..</code>&nbsp; have special meaning. Implementations may define 
additional filenames that have special meaning.</p>
<blockquote>
  <p><i>[Note:</i> Most operating systems prohibit the ASCII control characters 
  (0x00-0x1F) in filenames.</p>
  <p>Windows prohibits the characters 0x00-0x1F, <code>&quot;</code>,<code> 
  *</code>,<code>&nbsp;:</code>,<code> &lt;</code>,<code> &gt;</code>,<code>&nbsp;?</code>,<code> 
  \</code>,<code> /</code>, and<code> |</code>&nbsp;<i>--end note]</i></p>
</blockquote>
<p><b><i><a name="Path">Path</a></i></b><br>
A sequence of elements that identify 
a location within a filesystem. The elements are the <i>root-name<sub>opt</sub></i>, <i>
root-directory<sub>opt</sub></i>, and an optional sequence of filenames. [<i>Note:</i> 
A <a href="#Pathname">pathname</a> is the concrete representation of a path. <i>--end note</i>]</p>
<p><b><i><a name="Absolute-path">Absolute path</a></i></b><br>
&nbsp;A path that uniquely 
identifies a file. The format is implementation defined. </p>
<blockquote>
  <p><i>[Note:</i> For POSIX-like implementations, including<b> </b>Unix 
  variants, Linux, and Mac OS X, only paths 
  that begin with a slash are absolute paths.</p>
  <p>For Windows-like implementations, including <a href="http://www.cygwin.com/">
  Cygwin</a> and
  <a href="http://www.mingw.org/">MinGW</a>, only paths that begin with a drive 
  specifier followed by a slash, or begin with two slashes, are absolute paths.&nbsp;<i>--end 
  note]</i></p>
</blockquote>
<p><b><a name="Relative-path">Relative path</a></b><br>
A path that uniquely 
identifies a file only when considered relative to some other path. [<i>Note:</i> 
Paths &quot;.&quot; and &quot;..&quot; are considered to be relative paths. <i>--end note</i>]</p>
<p><i><b><a name="Pathname">Pathname</a></b></i><br>
A character string that represents a 
path. Pathnames are formatted according to the generic pathname format or the 
native pathname format.</p>
<p><b><i><a name="generic-pathname-format">Generic pathname format</a></i></b></p>
<blockquote>
<p><i>pathname:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; root-name<sub>opt</sub> 
root-directory<sub>opt</sub> relative-path<sub>opt</sub></i></p>
<p><i>root-name:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
implementation-defined</i></p>
<blockquote>
  <blockquote>
<p>[<i>Note:</i> Most POSIX and Windows based operating system define a name 
beginning with two slashes (or backslashes, for Windows) as a root-name 
identifying network locations. Windows defines a single letter followed by a
<code>&quot;:&quot;</code> as a root-name identifying a disc drive. <i>--end note</i>]</p>
  </blockquote>
</blockquote>
<p><i>root-directory:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
directory-separator</i></p>
<p><i>relative-path:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
filename<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; relative-path 
directory-separator<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; relative-path 
directory-separator filename</i></p>
<p><i>filename:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; name<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </i><code>&quot;.&quot;</code><i><br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </i><code>
&quot;..&quot;</code></p>
<p><i>directory-separator:<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <code>&quot;/&quot;<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &quot;/&quot;</code> directory-separator</i></p>
<p>Multiple successive <i>directory-separator</i> characters are considered to 
be the same as one <i>directory-separator</i> character. The <i>filename</i>
<code>&quot;.&quot;</code> is considered to be a reference to the current directory. The
<i>filename</i> <code>&quot;..&quot;</code> is considered to be a reference to the current 
directory. Specific <i>filenames</i> may have special meaning for a particular 
operating system.</p>
</blockquote>
<p><b><i><a name="native-pathname-format">Native pathname format</a></i></b><br>
An implementation defined format. [<i>Note:</i> For POSIX-like operating 
systems, the native format is the same as the generic format. For Windows, the 
native format is similar to the generic format, but the directory-separator 
characters can be either slashes or backslashes. <i>--end note</i>]</p>
<p><i><b><a name="Link">Link</a></b></i><br>
A directory entry object that associates a 
filename with a file. On some file systems, several directory entries can 
associate names with the same file.</p>
<p><b><i><a name="Hard-link">Hard link</a></i></b><br>
A link to an existing file. Some 
file systems support multiple hard links to a file. If the last hard link to a 
file is removed, the file itself is removed.</p>
<blockquote>
<p>[<i>Note:</i> A hard link can be thought of as a shared-ownership smart 
pointer to a file.<i> -- end note</i>]<i> </i></p>
</blockquote>
<p><i><a name="Symbolic-link">S<b>ymbolic link</b></a></i><br>
A type of file with the 
property that when the file is encountered during pathname resolution, a string 
stored by the file is used to modify the pathname resolution.</p>
<blockquote>
<p>[<i>Note:</i> A symbolic link can be thought of as a raw pointer to a file. 
If the file pointed to does not exist, the symbolic link is said to be a 
&quot;dangling&quot; symbolic link.<i> -- end note</i>]<i> </i></p>
</blockquote>
<p><b><i><a name="Race-condition">Race condition</a></i></b><br>
The condition that occurs 
when multiple threads, processes, or computers interleave access and 
modification of 
the same object within a file system.</p>
<p><b><i><a name="Dot">Dot</a>, Dot Dot:</i></b> Synonyms for the filenames <code>&quot;.&quot;</code> 
and <code>&quot;..&quot;</code>, respectively. The dot filename names the current 
directory. The dot dot filename names the parent directory.</p>
<h2><a name="Header-filesystem-synopsis">Header <code>&lt;filesystem&gt;</code> synopsis</a></h2>
  
    <div align="center">
      <center>

<table border="1" cellpadding="3" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" bgcolor="#E0E0E0" width="90%">
  <tr>
    <td>
  <p><i>The proposal places the library in namespace<code> std::tr2::filesystem</code>. 
  Rationale is that the library uses several names that don't seem 
  appropriate to go directly into namespace<code> tr2</code> since full 
  standardization would then put the names into <code>std</code>. The function names <code>
  remove</code> and <code>rename</code> are of particular concern because these 
  functions differ in behavior from current standard library functions with 
  those names. It also doesn't seem desirable to preempt names like <code>equivalent</code> 
  and <code>status</code>.</i></p>
  <p><i>Would the LWG prefer something shorter, such as<code> std::tr2::files</code>?</i></p>
    </td>
  </tr>
</table>

      </center>
    </div>

<pre>  namespace std { namespace tr2 {
  {
    namespace filesystem
    {
      class <a href="#class-path">path</a>;
      class <a href="#Class-filesystem_error">filesystem_error</a>;
      class <a href="#Class-directory_entry">directory_entry</a>;
      class <a href="#Class-directory_iterator">directory_iterator</a>;
      class <a href="#Class-recursive_directory_iterator">recursive_directory_iterator</a>;
      class <a href="#file_status">file_status</a>;

      void swap(path&amp; lhs, path&amp; rhs);
      bool lexicographical_compare(path::iterator first1, path::iterator last1,
                                   path::iterator first2, path::iterator last2);

      bool operator==(const path&amp; lhs, const path&amp; rhs);
      bool operator!=(const path&amp; lhs, const path&amp; rhs);
      bool operator&lt; (const path&amp; lhs, const path&amp; rhs);
      bool operator&lt;=(const path&amp; lhs, const path&amp; rhs);
      bool operator&gt; (const path&amp; lhs, const path&amp; rhs);
      bool operator&gt;=(const path&amp; lhs, const path&amp; rhs);

      path operator/ (const path&amp; lhs, const path&amp; rhs);

      ostream&amp;  operator&lt;&lt;( ostream&amp; os, const path&amp; p );
      wostream&amp; operator&lt;&lt;( wostream&amp; os, const path&amp; p );
      istream&amp;  operator&gt;&gt;( istream&amp; is, path&amp; p );
      wistream&amp; operator&gt;&gt;( wistream&amp; is, path&amp; p )

      enum <a name="file_type">file_type</a> { status_error, file_not_found, regular_file, directory_file,
                       symlink_file, block_file, character_file, fifo_file, socket_file,
                       type_unknown
                     };

      struct <a name="space_info">space_info</a>  // returned by <a href="#space" style="text-decoration: none">space</a> function
      {
        uintmax_t capacity;
        uintmax_t free; 
        uintmax_t available; // free space available to a non-privileged process
      };

      enum class <a name="copy_option">copy_option</a>
      {
        none
        fail_if_exists = none,
        overwrite_if_exists
      };

      enum class <a name="symlink_option">symlink_option</a>
      {
        none
        no_recurse = none,
        recurse
      };

      // <a href="#Operational-functions">operational functions</a>

      path         <a href="#absolute">absolute</a>(const path&amp; p, const path&amp; base=current_path());

      void         <a href="#copy">copy</a>(const path&amp; from, const path&amp; to);
      void         <a href="#copy">copy</a>(const path&amp; from, const path&amp; to, error_code&amp; ec);

      void         <a href="#create_directory">copy_directory</a>(const path&amp; from, const path&amp; to);
      void         <a href="#create_directory">copy_directory</a>(const path&amp; from, const path&amp; to, error_code&amp; ec);

      void         <a href="#copy_file">copy_file</a>(const path&amp; from, const path&amp; to);
      void         <a href="#copy_file">copy_file</a>(const path&amp; from, const path&amp; to, error_code&amp; ec);
      void         <a href="#copy_file">copy_file</a>(const path&amp; from, const path&amp; to, <a href="#copy_option">copy_option</a> option);
      void         <a href="#copy_file">copy_file</a>(const path&amp; from, const path&amp; to, <a href="#copy_option">copy_option</a> option,
                             error_code&amp; ec);

      void         <a href="#copy_symlink">copy_symlink</a>(const path&amp; existing_symlink, const path&amp; new_symlink);
      void         <a href="#copy_symlink">copy_symlink</a>(const path&amp; existing_symlink, const path&amp; new_symlink, error_code&amp; ec);

      bool         <a href="#create_directories">create_directories</a>(const path&amp; p);
      bool         <a href="#create_directories">create_directories</a>(const path&amp; p, error_code&amp; ec);

      bool         <a href="#create_directory">create_directory</a>(const path&amp; p);
      bool         <a href="#create_directory">create_directory</a>(const path&amp; p, error_code&amp; ec);

      void         <a href="#create_directory_symlink">create_directory_symlink</a>(const path&amp; to, const path&amp; new_symlink);
      void         <a href="#create_directory_symlink">create_directory_symlink</a>(const path&amp; to, const path&amp; new_symlink, error_code&amp; ec);

      void         <a href="#create_hard_link">create_hard_link</a>(const path&amp; to, const path&amp; new_hard_link);
      void         <a href="#create_hard_link">create_hard_link</a>(const path&amp; to, const path&amp; new_hard_link, error_code&amp; ec);

      void         <a href="#create_symlink">create_symlink</a>(const path&amp; to, const path&amp; new_symlink);
      void         <a href="#create_symlink">create_symlink</a>(const path&amp; to, const path&amp; new_symlink, error_code&amp; ec);

      path         <a href="#current_path">current_path</a>();
      path         <a href="#current_path">current_path</a>(error_code&amp; ec);
      void         <a href="#current_path">current_path</a>(const path&amp; p);
      void         <a href="#current_path">current_path</a>(const path&amp; p, error_code&amp; ec);

      bool         <a href="#exists">exists</a>(file_status s);
      bool         <a href="#exists">exists</a>(const path&amp; p);
      bool         <a href="#exists">exists</a>(const path&amp; p, error_code&amp; ec);

      bool         <a href="#equivalent">equivalent</a>(const path&amp; p1, const path&amp; p2);
      bool         <a href="#equivalent">equivalent</a>(const path&amp; p1, const path&amp; p2, error_code&amp; ec);

      uintmax_t    <a href="#file_size">file_size</a>(const path&amp; p);
      uintmax_t    <a href="#file_size">file_size</a>(const path&amp; p, error_code&amp; ec);

      uintmax_t    <a href="#hard_link_count">hard_link_count</a>(const path&amp; p);
      uintmax_t    <a href="#hard_link_count">hard_link_count</a>(const path&amp; p, error_code&amp; ec);

      const path&amp;  <a href="#initial_path">initial_path</a>();
      const path&amp;  <a href="#initial_path">initial_path</a><code>(error_code&amp; ec</code>);

      bool         <a href="#is_directory">is_directory</a>(file_status s);
      bool         <a href="#is_directory2">is_directory</a>(const path&amp; p);
      bool         <a href="#is_directory2">is_directory</a>(const path&amp; p, error_code&amp; ec);

      bool         <a href="#is_empty">is_empty</a>(const path&amp; p);
      bool         <a href="#is_empty">is_empty</a>(const path&amp; p, error_code&amp; ec);

      bool         <a href="#is_other">is_other</a>(file_status s);
      bool         <a href="#is_other2">is_other</a>(const path&amp; p,);
      bool         <a href="#is_other2">is_other</a>(const path&amp; p, error_code&amp; ec);

      bool         <a href="#is_regular_file">is_regular_file</a>(file_status s); 
      bool         i<a href="#is_regular_file2">s_regular_file</a>(const path&amp; p);
      bool         i<a href="#is_regular_file2">s_regular_file</a>(const path&amp; p, error_code&amp; ec);

      bool         <a href="#is_symlink">is_symlink</a>(file_status s);
      bool         <a href="#is_symlink2">is_symlink</a>(const path&amp; p);
      bool         <a href="#is_symlink2">is_symlink</a>(const path&amp; p, error_code&amp; ec);

      time_t       <a href="#last_write_time">last_write_time</a>(const path&amp; p);
      time_t       <a href="#last_write_time">last_write_time</a>(const path&amp; p, error_code&amp; ec);
      void         <a href="#last_write_time2">last_write_time</a>(const path&amp; p, const time_t new_time);
      void         <a href="#last_write_time2">last_write_time</a>(const path&amp; p, const time_t new_time, error_code&amp; ec);

      path         <a href="#read_symlink">read_symlink</a>(const path&amp; p);
      path         <a href="#read_symlink">read_symlink</a>(const path&amp; p, error_code&amp; ec);

      bool         <a href="#remove">remove</a>(const path&amp; p);
      bool         <a href="#remove">remove</a>(const path&amp; p, error_code&amp; ec);

      uintmax_t    <a href="#remove_all">remove_all</a>(const path&amp; p);
      uintmax_t    <a href="#remove_all">remove_all</a>(const path&amp; p, error_code&amp; ec);

      void         <a href="#rename">rename</a>(const path&amp; from, const path&amp; to);
      void         <a href="#rename">rename</a>(const path&amp; from, const path&amp; to, error_code&amp; ec);

      void         <a href="#resize_file">resize_file</a>(const path&amp; p, uintmax_t size);
      void         <a href="#resize_file2">resize_file</a>(const path&amp; p, uintmax_t size, error_code&amp; ec);

      <a href="#space_info">space_info</a>   <a href="#space">space</a>(const path&amp; p);
      <a href="#space_info">space_info</a>   <a href="#space">space</a>(const path&amp; p, error_code&amp; ec);

      <a href="#file_status">file_status</a>  <a href="#status">status</a>(const path&amp; p);
      <a href="#file_status">file_status</a>  <a href="#status">status</a>(const path&amp; p, error_code&amp; ec);

      bool         <a href="#status_known">status_known</a>(file_status s);

      <a href="#file_status">file_status</a>  <a href="#symlink_status">symlink_status</a>(const path&amp; p);
      <a href="#file_status">file_status</a>  <a href="#symlink_status">symlink_status</a>(const path&amp; p, error_code&amp; ec);

      path         <a href="#system_complete">system_complete</a>(const path&amp; p);
      path         <a href="#system_complete">system_complete</a>(const path&amp; p, error_code&amp; ec);

      path         <a href="#temp_directory_path">temp_directory_path</a>();
      path         <a href="#temp_directory_path">temp_directory_path</a>(error_code&amp; ec);

      path         <a href="#unique_path">unique_path</a>(const path&amp; model=&quot;%%%%-%%%%-%%%%-%%%%&quot;);
      path         <a href="#unique_path">unique_path</a>(const path&amp; model, error_code&amp; ec);

    } // namespace filesystem
  }} // namespaces std and tr2</pre>
  
<h2><a name="Error-reporting">Error reporting</a></h2>
<p>Filesystem library functions often provide two overloads, one that 
throws an exception to report file system errors, and another that sets an
<code>error_code</code>.</p>
<p>[<i>Note:</i> This supports two common use cases:</p>
  <ul>
    <li dir="ltr">
  <p dir="ltr">Uses where file system errors are truly exceptional and indicate a serious 
  failure. Throwing an exception is the most appropriate response. This is the 
  recommended approach for much everyday programming.</li>
  </ul>
  <ul>
    <li>Uses where file system system errors are routine and do not necessarily represent 
  failure. Returning an error code is the most appropriate response. This allows 
  application specific error handling, including simply ignoring the error. Code 
  littered with <code>try</code> - <code>catch</code> blocks is an indication 
  that error reporting by <code>error_code</code> may be more appropriate.</li>
    </ul>
  <p><i>--end note</i>]</p>
<p>Functions <b>not</b> having an argument of type<code> error_code&amp;</code> 
report errors as follows, unless otherwise specified:</p>
  <ul>
  <li>
  <p>When a call by the 
  implementation to an operating system or other underlying API results in an 
  error that prevents the function from meeting its specifications, an exception 
  of type
<code>filesystem_error</code> is thrown.</li>
  </ul>
  <ul>
  <li>
  <p>Failure to allocate storage is reported by throwing an exception as described in the C++ standard, 
  17.6.4.10 [res.on.exception.handling].</li>
  </ul>
  <ul>
  <li>
  <p>Destructors throw nothing.</li>
  </ul>
  <p>Functions having an argument of type<code> error_code&amp;</code> report errors as follows, unless otherwise 
  specified:</p>
<ul>
  <li>
  <p>If a call by the 
  implementation to an operating system or other underlying API results in an 
  error that prevents the function from meeting its specifications, the<code> error_code&amp;</code> argument is set as 
  appropriate appropriate for the specific error. Otherwise, <code>clear()</code> 
  is called on the<code> error_code&amp;</code> argument.</li>
</ul>
<ul>
  <li>
  <p>Failure to allocate storage is reported by 
  throwing an exception as described in the C++ standard, 
  17.6.4.10 [res.on.exception.handling].</li>
</ul>
<h2><a name="class-path">Class <code>path</code></a></h2>
<p>An object of class <code>path</code> represents a <a href="#Path">path</a>, 
and contains a <a href="#Pathname">pathname</a> Such an object is concerned only with the lexical and syntactic aspects 
of a path. The path may not actually exist in external storage, and may contain pathnames which are not even valid for the current operating 
system. </p>
  
<pre>  namespace std { namespace tr2 {
  {
    namespace filesystem
    {
      class path
      {
      public:
        typedef <b><i><a href="#value_type">see below</a></i></b>                          value_type;  // char for POSIX, wchar_t for Windows
        typedef basic_string&lt;value_type&gt;           string_type;
        typedef codecvt&lt;wchar_t, char, mbstate_t&gt;  codecvt_type;

        // <a href="#path-constructors">constructors</a> and destructor
        path();
        path(const path&amp; p);

        template &lt;class <a href="#Source">Source</a>&gt;
          path(Source const&amp; source, const codecvt_type&amp; cvt=codecvt());

        template &lt;class <a href="#InputIterator">InputIterator</a>&gt;
          path(InputIterator begin, InputIterator end, const codecvt_type&amp; cvt=codecvt());

       ~path();

        // <a href="#path-assignments">assignments</a>
        path&amp; operator=(const path&amp; p);

        template &lt;class <a href="#Source">Source</a>&gt;
          path&amp; operator=(Source const&amp; source);

        template &lt;class <a href="#Source">Source</a>&gt;
          path&amp; assign(Source const&amp; source, const codecvt_type&amp; cvt)

        template &lt;class <a href="#InputIterator">InputIterator</a>&gt;
          path&amp; assign(InputIterator begin, InputIterator end, const codecvt_type&amp; cvt=codecvt());

        // <a href="#path-appends">appends</a>
        path&amp; operator/=(const path&amp; p);

        template &lt;class <a href="#Source">Source</a>&gt;
          path&amp; operator/=(Source const&amp; source);

        template &lt;class <a href="#Source">Source</a>&gt;
          path&amp; append(Source const&amp; source, const codecvt_type&amp; cvt);

        template &lt;class <a href="#InputIterator">InputIterator</a>&gt;
          path&amp; append(InputIterator begin, InputIterator end, const codecvt_type&amp; cvt=codecvt());

        // <a href="#path-modifiers">modifiers</a>
        void  <a href="#path-clear">clear</a>();
        path&amp; <a href="#absolute">make_absolute</a>(const path&amp; base);
        path&amp; <a href="#path-make_preferred">make_preferred</a>();  // POSIX: no effect. Windows: convert slashes to backslashes
        path&amp; <a href="#path-remove_filename">remove_filename</a>();
        path&amp; <a href="#path-replace_extension">replace_extension</a>(const path&amp; new_extension = path());
        void  <a href="#path-swap">swap</a>(path&amp; rhs);

        // <a href="#path-native-format-observers">native format observers</a>
        const string_type&amp;  <a href="#native">native</a>() const;  // native format, encoding
        const value_type*   <a href="#c_str">c_str</a>() const;   // native().c_str()

        template &lt;class String&gt;
        String <a href="#string-template">string</a>(const codecvt_type&amp; cvt=codecvt()) const;                // native format

        const string        <a href="#string">string</a>(const codecvt_type&amp; cvt=codecvt()) const;   // native format
        const wstring       <a href="#wstring">wstring</a>(const codecvt_type&amp; cvt=codecvt()) const;  // ditto
        const u16string     <a href="#u16string">u16string</a>() const;                                 // ditto
        const u32string     <a href="#u32wstring">u32string</a>() const;                                 // ditto

        // <a href="#path-generic-format-observers">generic format observers</a>
        template &lt;class String&gt;
        String <a href="#generic_string-template">generic_string</a>() const;

        const string        <a href="#generic_string">generic_string</a>(const codecvt_type&amp; cvt=codecvt()) const;   // generic format
        const wstring       <a href="#generic_wstring">generic_wstring</a>(const codecvt_type&amp; cvt=codecvt()) const;  // ditto
        const u16string     <a href="#generic_u16string">generic_u16string</a>() const;                                 // ditto
        const u32string     <a href="#generic_u32wstring">generic_u32string</a>() const;                                 // ditto

        // <a href="#path-decomposition">decomposition</a>
        path  <a href="#path-root_name">root_name</a>() const;
        path  <a href="#path-root_directory">root_directory</a>() const;
        path  <a href="#path-root_path">root_path</a>() const;
        path  <a href="#path-relative_path">relative_path</a>() const;
        path  <a href="#path-parent_path">parent_path</a>() const;
        path  <a href="#path-filename">filename</a>() const;
        path  <a href="#path-stem">stem</a>() const;
        path  <a href="#path-extension">extension</a>() const;

        // <a href="#path-query">query</a>
        bool <a href="#path-query">empty</a>() const;
        bool <a href="#path-has_root_name">has_root_name</a>() const;
        bool <a href="#path-has_root_directory">has_root_directory</a>() const;
        bool <a href="#path-has_root_path">has_root_path</a>() const;
        bool <a href="#path-has_relative_path">has_relative_path</a>() const;
        bool <a href="#path-has_parent_path">has_parent_path</a>() const;
        bool <a href="#path-has_filename">has_filename</a>() const;
        bool <a href="#path-has_stem">has_stem</a>() const;
        bool <a href="#path-has_extension">has_extension</a>() const;
        bool <a href="#path-is_absolute">is_absolute</a>() const;
        bool <a href="#path-is_relative">is_relative</a>() const;

        // <a href="#path-iterators">iterators</a>
        class iterator;
        typedef iterator const_iterator;

        iterator begin() const;
        iterator end() const;
        
        // <a href="#path_encoding">encoding conversion</a>
        static locale <a href="#path-imbue">imbue</a>( const locale&amp; loc );
        static const codecvt_type &amp; <a href="#path-codecvt">codecvt</a>();

      private:
        string_type pathname;  // <b><i>exposition only</i></b>
      };

    } // namespace filesystem
  }} // namespaces std and tr2</pre>
  
<p><code><a name="value_type">value_type</a></code> is an implementation-defined 
<code>typedef</code> for the 
character type used by the implementation to represent pathnames.</p>
<p>If the value type of&nbsp; [<code>begin</code>,<code>end</code>) 
  or <code>source</code> arguments for member functions is not <code>value_type</code>, 
and no <code>cvt</code> argument is supplied, conversion to <code>value_type</code> 
occurs using an imbued locale. This imbued locale is initialized with a <code>
codecvt</code> facet appropriate for the operating system.</p>
<blockquote>
<p>For Apple OS X implementations, <code>path::value_type</code> 
is <code>char</code>. The default imbued locale provides a UTF-8 <code>codecvt</code> 
facet. [<i>Rationale:</i> &quot;All BSD system functions expect their string 
parameters to be in UTF-8 encoding and nothing else.&quot; See
<a href="http://developer.apple.com/mac/library/documentation/MacOSX/Conceptual/BPInternational/Articles/FileEncodings.html">
Apple docs</a>. <i>-- end rationale</i>]</p>
<p>For Windows-like implementations, including 
  <a href="http://www.cygwin.com/">Cygwin</a> and
<a href="http://www.mingw.org/">MinGW</a>, <code>path::value_type</code> is <code>
wchar_t</code>. The default imbued locale provides a <code>codecvt</code> facet 
that invokes Windows <code>MultiByteToWideChar</code> or <code>
WideCharToMultiByte</code> API's with a codepage of <code>CP_THREAD_ACP</code> 
if Windows <code>AreFileApisANSI()</code>is true, otherwise codepage <code>
CP_OEMCP</code>. [<i>Rationale:</i> this is the current behavior of C and C++ 
programs that perform file operations using narrow character string to identify 
paths. Changing this in the Filesystem library would be too surprising, 
particularly where user input is involved. <i>-- end rationale</i>]</p>
<p>For all other implementations, including<b> </b>Linux, <code>path::value_type</code> 
is <code>char</code>. The default imbued locale is<code> locale(&quot;&quot;)</code>. 
[<i>Rationale:</i> ISO C specifies this as &quot;the locale-specific native 
environment&quot;, while POSIX says it &quot;Specifies an implementation-defined native 
environment.&quot; <i>-- end rationale</i></p>
</blockquote>
<p>For member functions described as returning <code>const string</code>, <code>
const wstring</code>, <code>const u16string</code>, or <code>const u32string</code>, 
implementations are permitted to return <code>const string&amp;</code>, <code>const 
wstring&amp;</code>, <code>const u16string&amp;</code>, or <code>const u32string&amp;</code>, 
respectively.</p>
<blockquote>
<p>[<i>Note:</i> This allows implementations to avoid unnecessary copies when no 
conversion is required. 
Return-by-value is specified as
<code>const</code> to ensure programs won't break if moved to a return-by-reference 
implementation. <i>-- 
end note</i>]</p>
</blockquote>
<p><code><a name="InputIterator">InputIterator</a></code> is required to meet the <code>RandomIterator</code> 
requirements. The iterator's value type is required to be <code>char</code>, <code>
  wchar_t</code>, <code>char16_t</code>, or <code>char32_t</code>.</p>
<p><code><a name="Source">Source</a></code> is required to be one of:</p>
<ul>
  <li>
  <p>A container with a value type of <code>char</code>, <code>
  wchar_t</code>, <code>char16_t</code>, or <code>char32_t</code>.</li>
  <li>
  <p>An iterator for a null terminated byte-string. The value type is required 
  to be <code>char</code>, <code>wchar_t</code>, <code>char16_t</code>, or <code>
  char32_t</code>.</li>
  <li>
  <p>A C-array. The value type is required to be <code>char</code>, <code>
  wchar_t</code>, <code>char16_t</code>, or <code>char32_t</code>.</li>
  <li>
  <p>A <code>directory_entry</code>.</li>
</ul>
<p>The specifications for <code>path</code> functions require that 
arguments in the generic pathname format be converted to native pathname format 
as they are stored in <code>pathname</code>. If the native format requires 
regular file paths and directory paths to be formatted differently, the 
implementation shall determine which format to use according to whether or not 
the last element of the generic format string is a separator. [<i>Example:</i> 
On <a href="http://en.wikipedia.org/wiki/OpenVMS">OpenVMS</a>, a path 
constructed from <code>&quot;/cats/jane&quot;</code> would considered a regular file 
path, and have a native format of <code>&quot;[CATS]JANE&quot;</code>, while a 
path constructed from <code>&quot;/cats/jane/&quot;</code> would be considered a 
directory path, and have a native format of <code>&quot;[CATS.JANE]&quot;</code>.
<i>--end example</i>] [<i>Note</i>: POSIX and Windows use the same native format 
for both regular file and directory pathnames, so this paragraph does not apply to 
them. <i>--end note</i>]</p>

    <div align="center">
      <center>

<table border="1" cellpadding="3" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" bgcolor="#E0E0E0" width="90%">
  <tr>
    <td>
    <p><i>Class <code>path</code> does not currently map invalid characters in 
    filenames to valid characters. In the future we might add something like 
    this:</i></p>
    <blockquote>
<p><i>When converting filenames to the native operating system format, 
implementations are encouraged, but not required, to convert otherwise invalid 
characters or character sequences to valid characters or character sequences. 
Such conversions are implementation-defined.</i></p>
<blockquote>
<p><i>[Note: Filename conversion allows much wider portability of both 
programs and filenames that would otherwise be possible.</i></p>
<p><i>Implementations are encouraged to base conversion on existing standards or 
practice. Examples include the Uniform Resource Locator escape syntax of a percent sign (<code>'%'</code>) 
followed by two hex digits representing the character value. On OpenVMS, which does not allow percent signs in filenames, a dollar sign (<code>'$'</code>) 
followed by two hex digits is the existing practice, as is converting lowercase 
letters to uppercase. -- end note.]</i></p>
</blockquote>
    </blockquote>
    </td>
  </tr>
</table>

      </center>
    </div>

<h3> <a name="path-constructors"> <code>
<font size="4">path</font></code> constructors</a></h3>
  
<pre>path();</pre>
  
<blockquote>
  <p><i>Postcondition:</i> <code>empty()</code>.</p>
  </blockquote>
  
<pre>template &lt;class <a href="#Source">Source</a>&gt;
  path(Source const&amp; source, const codecvt_type&amp; cvt=codecvt());</pre>
  
  
<pre>template &lt;class <a href="#InputIterator">InputIterator</a>&gt;
  path(InputIterator begin, InputIterator end, const codecvt_type&amp; cvt=codecvt());</pre>
  
<blockquote>
  <p><i>Effects:</i> Stores the contents [<code>begin</code>,<code>end</code>) 
  or <code>source</code> in <code>pathname</code>. If the contents are in the 
  generic format and the generic format is unacceptable to the operating 
  system's API, they are converted to the native format. [<i>Note:</i> For 
  POSIX and Windows  implementations, the generic format is already 
  acceptable as a native format, so no generic to native conversion is 
  performed. <i>--end note</i>]</p>
  <p>
  <i>Remarks:</i> If the value type of&nbsp; [<code>begin</code>,<code>end</code>) 
  or <code>source</code> is not <code>value_type</code>, conversion is performed 
  by <code>cvt</code>.</p>
</blockquote>
<h3> <a name="path-assignments"> <code>
<font size="4">path</font></code> assignments</a></h3>
  
<pre>template &lt;class <a href="#Source">Source</a>&gt;
  path&amp; operator=(Source const&amp; source);</pre>
  
  
<pre>template &lt;class <a href="#Source">Source</a>&gt;
  path&amp; assign(Source const&amp; source, const codecvt_type&amp; cvt);</pre>
  
  
<pre>template &lt;class <a href="#InputIterator">InputIterator</a>&gt;
  path&amp; assign(InputIterator begin, InputIterator end, const codecvt_type&amp; cvt=codecvt());</pre>
  
<blockquote>
  <p><i>Effects:</i> Stores the contents [<code>begin</code>,<code>end</code>) 
  or <code>source</code> in <code>pathname</code>. If the contents are in the 
  generic format, they are converted to the native format. [<i>Note:</i> For 
  POSIX and Windows based implementations, the generic format is already 
  acceptable as a native format, so no generic to native conversion is 
  performed. <i>--end note</i>]</p>
  <p>
  <i>Returns: </i><code>*this</code></p>
  <p>
  <i>Remarks:</i> If the value type of&nbsp; [<code>begin</code>,<code>end</code>) 
  or <code>source</code> is not <code>value_type</code>, conversion is performed 
  by <code>cvt</code>.</p>
  </blockquote>
<h3> <a name="path-appends"><code><font size="4"> path</font></code> appends</a></h3>
  <p>The append operations use <code>operator/=</code> to denote their semantic 
  effect of appending the platform's preferred directory separator when needed. The 
  preferred 
  directory separator is implementation-defined.</p>
<blockquote>
    <p align="left">[<i>Note: </i>For POSIX-like implementations, including<b> </b>
    Unix variants, Linux, and Mac OS X, the preferred directory separator is a 
    single forward slash.</p>
    <p align="left">For Windows-like implementations, including 
  <a href="http://www.cygwin.com/">Cygwin</a> and
    <a href="http://www.mingw.org/">MinGW</a>, the preferred directory 
    separator is a single backslash.<i>--end note</i>]</p>
      </blockquote>
  
<pre>path&amp; operator/=(const path&amp; p);</pre>
  
<blockquote>
  <p><i>Effects:</i></p>
  <blockquote>
    <p>Appends the preferred directory separator to the contained pathname, unless:</p>
    <ul>
    <li>
    <p>an added separator 
    would be redundant, or</li>
    <li>
    <p>would change an relative path to an absolute path, or</li>
    <li>
    <p><code>p.empty()</code>, or</li>
    <li>
    <p><code>*p.native().cbegin()</code> is a directory separator.</li>
  </ul>
    <p>Appends <code>p.native()</code> to <code>pathname</code>.</p>
  </blockquote>
  <p><i>Returns: </i><code>*this</code></p>
</blockquote>
  
<pre>template &lt;class <a href="#Source">Source</a>&gt;
  path&amp; operator/=(Source const &amp; source);</pre>
  
  
<pre>template &lt;class <a href="#Source">Source</a>&gt;
  path&amp; append(Source const &amp; source, const codecvt_type&amp; cvt);</pre>
  
  
<pre>template &lt;class <a href="#InputIterator">InputIterator</a>&gt;
  path&amp; append(InputIterator begin, InputIterator end, const codecvt_type&amp; cvt=codecvt());</pre>
  
<blockquote>
  <p><i>Effects:</i></p>
  <blockquote>
    <p>Appends a native directory separator to the contained pathname, unless:</p>
    <ul>
    <li>
    <p>an added separator 
    would be redundant, or</li>
    <li>
    <p>would change an relative path to an absoute path, or</li>
    <li>
    <p><code>p.empty()</code>, or</li>
    <li>
    <p><code>*p.native().cbegin()</code> is a separator.</li>
  </ul>
    <p>Appends the contents [<code>begin</code>,<code>end</code>) 
  or <code>source</code> to <code>pathname</code>. If the contents are in the 
    generic format, they are converted to the native format. [<i>Note:</i> For 
    POSIX and Windows based implementations, the generic format is already 
    acceptable as a native format, so no generic to native conversion is 
    performed. <i>--end note</i>]</p>
  </blockquote>
  <p><i>Remarks:</i> If the value type of&nbsp; [<code>begin</code>,<code>end</code>) 
  or <code>source</code> is not <code>value_type</code>, conversion is performed 
  by <code>cvt</code>.</p>
  <p><i>Returns: </i><code>*this</code></p>
  </blockquote>
  
<h3> <a name="path-modifiers"> <code>
<font size="4">path</font></code> modifiers</a></h3>
  
<pre>void <a name="path-clear">clear</a>();</pre>
  
<blockquote>
<p><i>Postcondition:</i> <code>this-&gt;empty()</code> is true.</p>
</blockquote>
  
<pre>path&amp; <a name="path-make_preferred">make_preferred</a>();</pre>
  
<blockquote>
  <p><i>Effects:</i> The contained pathname is converted to the preferred native 
  format. [<i>Note:</i> On Windows, the effect is to replace slashes with 
  backslashes. On POSIX, there is no effect. <i>-- end note</i>]</p>
  <p><i>Returns:</i> <code>*this</code></p>
</blockquote>

  

<pre>path&amp; <a name="path-remove_filename">remove_filename</a>();</pre>
  
<blockquote>
  <p><i>Returns: </i>As if, <code>*this = parent_path();</code></p>
  <p>[<i>Note:</i> This function is needed to efficiently implement <code>
  directory_iterator</code>. It is exposed to allow additional uses. The actual 
  implementation may be much more efficient than <code>*this = parent_path()</code>&nbsp; <i>-- end 
  note</i>]</p>
</blockquote>
  
<pre>path&amp; <a name="path-replace_extension">replace_extension</a>(const path&amp; new_extension = path());</pre>
  
<blockquote>
  <p><i>Postcondition: </i> <code>extension() == <i>replacement</i></code>, 
  where <code><i>replacement</i></code> is <code>new_extension</code> if <code>
  new_extension.empty() || new_extension[0] ==</code> the dot character, 
  otherwise <code><i>replacement</i></code> is the dot character followed by
  <code>new_extension</code>.</p>
  <p><i>Returns:</i> <code>*this</code></p>
</blockquote>
  
<pre><code>void <a name="path-swap">swap</a>(path&amp; rhs);</code></pre>
  
<blockquote>
  <p><i>Effects:</i> 
  Swaps the contents of the two paths.</p>
  <p><i>Throws: </i>
  nothing.</p>
  <p><i>Complexity: </i>
  constant time.</p>
</blockquote>

<h3> <a name="path-native-format-observers"><code><font size="4">path</font></code> 
native format observers</a></h3>
<p>The string returned by all native format observers is in the
<a href="#native-pathname-format">native pathname format</a>.</p>
  
<pre>const string_type&amp;  <a name="native">native</a>() const;</pre>
  
<blockquote>
<p><i>Returns:</i> <code>pathname</code>.</p>
<p><i>Throws:</i> nothing.</p>
</blockquote>
  
<pre>const value_type* <a name="c_str">c_str</a>() const;</pre>
  
<blockquote>
<p><i>Returns:</i> <code>pathname.c_str()</code>.</p>
<p><i>Throws:</i> nothing.</p>
</blockquote>
  
<pre>template &lt;class String&gt;
String <a name="string-template">string</a>(const codecvt_type&amp; cvt=codecvt()) const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>pathname</code>.</p>
<p><i>Remarks:</i> If <code>string_type</code> is a different type than <code>
String</code>, conversion is performed by <code>cvt</code>.</p>
</blockquote>
  
<pre>const string <a name="string">string</a>(const codecvt_type&amp; cvt=codecvt()) const;
const wstring <a name="wstring">wstring</a>(const codecvt_type&amp; cvt=codecvt()) const;
const u16string <a name="u16string">u16string</a>() const;
const u32wstring <a name="u32wstring">u32wstring</a>() const; </pre>
  
<blockquote>
<p><i>Returns:</i> <code>pathname</code>.</p>
<p><i>Remarks:</i> If <code>string_type</code> is a different type than 
function's return type, conversion is performed by <code>cvt</code>.</p>
<p>If <code>string_type</code> is the same type as the 
function's return type, the function is permitted to return by <code>const&amp;</code> 
rather than <code>const</code> value. [<i>Note:</i> For POSIX, this occurs for
<code>string()</code>, for Windows, <code>wstring()</code>. <i>--end note</i>]</p>
</blockquote>

<h3> <a name="path-generic-format-observers"><code><font size="4">path</font></code>
generic format observers</a></h3>
<p>The string returned by all generic format observers is in the
<a href="#generic-pathname-format">generic pathname format</a>.</p>
<p>[<i>Note:</i> For POSIX, no conversion occurs, since the native format and 
generic format are the same. For Windows, backslashes are converted to slashes
<i>--end note</i>]</p>
  
<pre>template &lt;class String&gt;
String <a name="generic_string-template">generic_string</a>(const codecvt_type&amp; cvt=codecvt()) const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>pathname</code>.</p>
<p><i>Remarks:</i> If <code>string_type</code> is a different type than <code>
String</code>, conversion is performed by
<code>cvt</code>.</p>
</blockquote>
  
<pre>const string <a name="generic_string">generic_string</a>(const codecvt_type&amp; cvt=codecvt()) const;
const wstring <a name="generic_wstring">generic_wstring</a>(const codecvt_type&amp; cvt=codecvt()) const;
const u16string <a name="generic_u16string">generic_u16string</a>() const;
const u32wstring <a name="generic_u32wstring">generic_u32wstring</a>() const; </pre>
  
<blockquote>
<p><i>Returns:</i> <code>pathname</code>.</p>
<p><i>Remarks:</i>&nbsp; If <code>string_type</code> is a different type than 
function's return type, conversion is performed by <code>cvt</code>.</p>
<p>If <code>string_type</code> is of the same type as the 
function's return type, and the generic format is the same as the native format, 
the function is permitted to return by <code>const&amp;</code> rather than <code>
const</code> value. [<i>Note:</i> For POSIX, this occurs for <code>string()</code>. 
It never occurs for Windows, because backslashes must be converted to slashes.
<i>--end note</i>]</p>
</blockquote>

<h3> <a name="path-decomposition"> <code><font size="4">path</font></code> 
decomposition</a></h3>
<p><span style="background-color: #E0E0E0"><i>See the
<a href="#Path-decomposition-table">Path decomposition table</a> for examples 
for values returned by decomposition functions. The
<a href="../../../boost/trunk/libs/filesystem/v3/doc/tutorial.html#Using-path-decomposition">Tutorial</a> may also be 
helpful.</i></span></p>
  
<pre>path <a name="path-root_name">root_name</a>() const;</pre>
  
<blockquote>
<p><i>Returns:</i> <i>root-name,</i> if <code>pathname</code> includes <i>
root-name</i>, otherwise <code>path()</code>. </p>
</blockquote>
  
<pre>path <a name="path-root_directory">root_directory</a>() const;</pre>
  
<blockquote>
<p><i>Returns:</i> <i>root-directory</i>, if <code>pathname</code> includes <i>
root-directory</i>, otherwise <code>path()</code>.</p>
<p>If <i>root-directory</i> is composed of <i>slash name</i>, <i>slash</i> is 
excluded from the returned string.</p>
</blockquote>
  
<pre>path <a name="path-root_path">root_path</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>root_name() / root_directory()</code></p>
</blockquote>
  
<pre>path <a name="path-relative_path">relative_path</a>() const;</pre>
  
<blockquote>
<p><i>Returns:</i> A <code>path</code> composed from <code>pathname</code>, if <code>
!empty()</code>, beginning 
with the first <i>filename</i> after <i>root-path</i>. Otherwise, <code>path()</code>.</p>
</blockquote>
  
<pre>path <a name="path-parent_path">parent_path</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>(empty() || begin() == --end()) ? path() : <i>pp</i></code>, where
  <code><i>pp</i></code> is constructed as if by 
  starting with an empty <code>path</code> and successively applying <code>
  operator/=</code> for each element in the range <code>begin()</code>, <code>
  --end()</code>.</p>
</blockquote>
  
<pre>path <a name="path-filename">filename</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>empty() ? path() : *--end()</code></p>
  <p>[<i>Example:</i></p>
  <blockquote>
    
    <pre><code>cout &lt;&lt; path(&quot;/foo/bar.txt&quot;).filename();</code> // outputs &quot;<code>bar.txt</code>&quot; (without the quotes)</pre>
    
  </blockquote>
  <p> <i>--end example</i>]</p>
</blockquote>
  
<pre>path <a name="path-stem">stem</a>(const path&amp; p) const;</pre>
  
<blockquote>
  <p><i>Returns:</i> if <code>p.filename()</code>contains a dot but does not 
  consist solely of one or to two dots, returns 
  the substring of <code>p.filename()</code> starting at its beginning and 
  ending at the last dot (the dot is not included). Otherwise, 
  returns <code>
  p.filename()</code>.</p>
  <p>[<i>Example:</i></p>
  <blockquote>
    
    <pre><code>cout &lt;&lt; path(&quot;/foo/bar.txt&quot;).stem();</code> // outputs &quot;<code>bar</code>&quot; (without the quotes)</pre>
    
    
    <pre>path p = &quot;foo.bar.baz.tar&quot;;
for (; !p.extension().empty(); p = p.stem())
  cout &lt;&lt; p.extension() &lt;&lt; '\n';
  // outputs: .tar
  //          .baz
  //          .bar</pre>
    
  </blockquote>
  <p> <i>--end example</i>]</p>
</blockquote>
  
<pre>path <a name="path-extension">extension</a>(const path&amp; p) const;</pre>
  
<blockquote>
  <p><i>Returns:</i> if <code>p.filename()</code> contains a dot but does not 
  consist solely of one or to two dots, returns 
  the substring of <code>p.filename()</code> starting at the rightmost dot 
  and ending at the path's end. Otherwise, returns an empty <code>path</code> 
  object. </p>
  <p><i>Remarks:</i> Implementations are permitted but not required to define additional 
  behavior for file systems which append additional elements to extensions, such 
  as alternate data streams or partitioned dataset names.</p>
  <p>[<i>Example:</i></p>
  <blockquote>
    
    <pre><code>cout &lt;&lt; path(&quot;/foo/bar.txt&quot;).extension(); //</code> outputs &quot;<code>.txt</code>&quot; (without the quotes)</pre>
    
  </blockquote>
  <p> <i>--end example</i>]</p>
  <p>[<i>Note:<b> </b></i>The dot is included in the return value so that it is 
  possible to distinguish between no extension and an empty extension.&nbsp; <i>-- end note</i>]</p>
  <p><i><span style="background-color: #E0E0E0">&nbsp;See
  <a href="http://permalink.gmane.org/gmane.comp.lib.boost.devel/199744">
  http://permalink.gmane.org/gmane.comp.lib.boost.devel/199744</a> for more 
  extensive rationale.</span></i></p>
</blockquote>
<h3> <a name="path-query"> <code><font size="4">path</font></code> query</a></h3>
  
<pre>bool <a name="path-empty">empty</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>m_pathname.empty()</code>.</p>
</blockquote>
  
<pre>bool <a name="path-has_root_path">has_root_path</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-root_path">root_path</a>().empty()</code></p>
</blockquote>
  
<pre>bool <a name="path-has_root_name">has_root_name</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-root_name">root_name</a>().empty()</code></p>
</blockquote>
  
<pre>bool <a name="path-has_root_directory">has_root_directory</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-root_directory">root_directory</a>().empty()</code></p>
</blockquote>
  
<pre>bool <a name="path-has_relative_path">has_relative_path</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-has_relative_path">relative_path</a>().empty()</code></p>
</blockquote>
  
<pre>bool <a name="path-has_parent_path">has_parent_path</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-parent_path">parent_path</a>().empty()</code></p>
</blockquote>
  
<pre>bool <a name="path-has_filename">has_filename</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-filename">filename</a>().empty()</code></p>
</blockquote>
  
<pre>bool <a name="path-has_stem">has_stem</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-stem">stem</a>().empty()</code></p>
</blockquote>
  
<pre>bool <a name="path-has_extension">has_extension</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>!<a href="#path-has_extension">extension</a>().empty()</code></p>
</blockquote>
  
<pre>bool <a name="path-is_absolute">is_absolute</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>true</code> 
  if the elements of <code>root_path()</code> uniquely identify a directory, else <code>false</code>.</p>
  <p>[<i>Note:</i> On POSIX,<code> 
  path(&quot;/foo&quot;).is_absolute()</code> returns <code>true</code>. On Windows, <code>
  path(&quot;/foo&quot;).is_absolute()</code> returns <code>false</code>. <i>--end note</i>]</p>
</blockquote>
  
<pre>bool <a name="path-is_relative">is_relative</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>!is_absolute()</code>.</p>
</blockquote>
<h3> <a name="path-iterators"> <code>
<font size="4">path</font></code> iterators</a></h3>
<p> A <code>path::iterator</code> is a constant iterator satisfying all 
the requirements of a bidirectional iterator (C++ Std, 24.1.4 Bidirectional 
iterators [lib.bidirectional.iterators]). Its <code>value_type</code> is <code>
path</code>.</p>
  <p>Calling any non-const member function of a <code>path</code> object 
  invalidates all iterators referring to elements of that object.</p>
<p> The forward traversal order is as follows:</p>
<ul>
  <li>
  <p>The <i>root-name</i> element, if present.</li>
  <li>
  <p>The <i>root-directory</i> element, if present.</li>
  <li>
  <p>Each successive <i>filename</i> element, if present.</li>
  <li>
  <p><i>Dot</i>, if one or more trailing non-root <i>slash</i> 
  characters are present.</li>
</ul>
  <p>The backward traversal order is the reverse of forward traversal.</p>
  
  <pre>iterator begin() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> An iterator for the first present element in the traversal 
  list above. If no elements are present, the end iterator.</p>
</blockquote>
  
<pre>iterator end() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> The end iterator.</p>
</blockquote>
 <h3><a name="path_encoding"><code><font size="4"> path</font></code> encoding</a> conversion</h3>
  
 <pre>static locale <a name="path-imbue">imbue</a>(const locale&amp; loc);</pre>
  
<blockquote>
  <p><i>Effects:</i> Stores <code>loc</code> as the default locale for all 
  objects of type <code>path</code>.</p>
  <p><i>Returns:</i> The previous default locale for all objects of type <code>
  path</code>.</p>
</blockquote>
  
<pre>static const codecvt_type&amp; <a name="path-codecvt">codecvt</a>();</pre>
  
<blockquote>
  <p><i>Returns:</i> The <code>codecvt</code> facet for the default locale for 
  all objects of type <code>path</code>.</p>
</blockquote>
<h3> <a name="path-non-member-functions"> <code><font size="4">path</font></code>
non-member functions</a></h3>
  
<pre>void swap( path&amp; lhs, path&amp; rhs )</pre>
  
<blockquote>
  <p><i>Effects: </i><code>
  lhs.swap(rhs)</code>.</p>
</blockquote>
  
  <pre>bool lexicographical_compare(path::iterator first1, path::iterator last1,
                             path::iterator first2, path::iterator last2)</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>true</code> if the sequence of <code>native()</code> 
  strings for the elements defined by the range <code>[first1,last1)</code> is 
  lexicographically less than the sequence of <code>native()</code> strings for 
  the elements defined by the range <code>[first2,last2)</code>. Returns <code>
  false</code> otherwise.</p>
  <p><i>Remarks:</i> If two sequences have the same number of elements and their 
  corresponding elements are equivalent, then neither sequence is 
  lexicographically less than the other. If one sequence is a prefix of the 
  other, then the shorter sequence is lexicographically less than the longer 
  sequence. Otherwise, the lexicographical comparison of the sequences yields 
  the same result as the comparison of the first corresponding pair of elements 
  that are not equivalent.</p>
  
  <pre>  for ( ; first1 != last1 &amp;&amp; first2 != last2 ; ++first1, ++first2) {
    if (first1-&gt;native() &lt; first2-&gt;native()) return true;
    if (first2-&gt;native() &lt; first1-&gt;native()) return false;
  }
  return first1 == last1 &amp;&amp; first2 != last2;</pre>
  
  <p>[<i>Note:</i> A <code>path</code> aware<code> lexicographical_compare</code> 
  is provided to avoid infinite recursion in<code> lexicographical_compare</code> 
  due to the <code>path</code> iterator's value type itself being <code>path</code>.
  <i>--end note</i>]</p>
</blockquote>
  
<pre>bool operator&lt; (const path&amp; lhs, const path&amp; rhs);</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>return lexicographical_compare(lhs.begin(), lhs.end(), 
  rhs.begin(), rhs.end())</code>.</p>
</blockquote>
  
<pre>bool operator&lt;=(const path&amp; lhs, const path&amp; rhs);</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>!(rhs &lt; lhs)</code>.</p>
</blockquote>
  
<pre>bool operator&gt; (const path&amp; lhs, const path&amp; rhs);</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>rhs &lt; lhs</code>.</p>
</blockquote>
  
<pre>bool operator&gt;=(const path&amp; lhs, const path&amp; rhs);</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>!(lhs &lt; rhs)</code>.</p>
</blockquote>
  
<pre>bool operator==(const path&amp; lhs, const path&amp; rhs);</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>!(lhs &lt; rhs) &amp;&amp; !(rhs &lt; lhs)</code>.</p>
  <p>[<i>Note:</i> Actual implementations may use an equivalent, but more 
  efficient, algorithm. <i>--end note</i>]</p>
  <p>[<i>Note:</i> <a name="Path-equality">Path equality</a> and path 
  equivalence have different semantics.</p>
  <p>Equality is determined by the <code>path</code> 
  non-member <code>operator==</code>, which considers the two path's lexical 
  representations only. Thus <code>path(&quot;foo&quot;) == &quot;bar&quot;</code> is never 
  <code>true</code>.</p>
  <p>Equivalence is determined by the <a href="#equivalent"><code>equivalent()</code></a> 
  non-member function, which determines if two paths <a href="#Path">resolve</a> to the same file system entity. 
  Thus <code>equivalent(&quot;foo&quot;, &quot;bar&quot;)</code> will be <code>true</code> 
  when both paths resolve to the same file.</p>
  <p>Programmers wishing to determine if two paths are &quot;the same&quot; must decide if 
  &quot;the same&quot; means &quot;the same representation&quot; or &quot;resolve to the same actual 
  file&quot;, and choose the appropriate function accordingly. <i>
  -- end note</i>]</p>
</blockquote>
  
<pre>bool operator!=(const path&amp; lhs, const path&amp; rhs);</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>!(lhs == rhs)</code>.</p>
</blockquote>
  
<pre>path operator/ (const path&amp; lhs, const path&amp; rhs);</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>path(lhs) /= rhs</code>.</p>
</blockquote>
<h3> <a name="path-non-member-operators"><code><font size="4">path</font></code></a><a name="path-inserter-extractor"> inserter 
  and extractor</a></h3>
<p> The inserter and extractor delimit the string with double-quotes (<code>&quot;</code>) 
to ensure that paths with embedded spaces will round trip correctly. Ampersand (<code>&amp;</code>) 
is used as an escape character, so the path can itself contain double quotes.</p>
  
<pre>template &lt;class Char, class Traits&gt;
basic_ostream&lt;Char, Traits&gt;&amp; operator&lt;&lt;(basic_ostream&lt;Char, Traits&gt;&amp; os, const path&amp; p)
</pre>
  
<blockquote>
  <p><i>Effects:</i>&nbsp;
  <code>os &lt;&lt;
  boost::io::quoted(p.string&lt;basic_string&lt;Char&gt;&gt;(), static_cast&lt;Char&gt;('&amp;'));</code></p>
  <p><i>Returns:</i>
   <code>os</code></p>
</blockquote>
  
<pre>template &lt;class Char, class Traits&gt;
inline basic_istream&lt;Char, Traits&gt;&amp; operator&gt;&gt;(basic_istream&lt;Char, Traits&gt;&amp; is, path&amp; p)
</pre>
  
<blockquote>
  <p><i>Effects:&nbsp; </i>
      <code>&nbsp;basic_string&lt;Char&gt; str;<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; is &gt;&gt; boost::io::quoted(str, 
  static_cast&lt;Char&gt;('&amp;'));<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; p = str;</code></p>
  <p><i>Returns:</i>
   <code>is</code></p>
  </blockquote>
<h3><a name="Class-filesystem_error">Class <code>filesystem_error</code></a></h3>
  
<pre>  namespace std { namespace tr2 {
  {
    namespace filesystem
    {
      class basic_filesystem_error : public system_error
      {
      public:
        filesystem_error();
        filesystem_error(const filesystem_error&amp;);
        <a href="#filesystem_error-2-arg">filesystem_error</a>(const string&amp; what_arg, error_code ec);
        <a href="#filesystem_error-3-arg">filesystem_error</a>(const string&amp; what_arg, const path&amp; p1, error_code ec);
        <a href="#filesystem_error-4-arg">filesystem_error</a>(const string&amp; what_arg, const path&amp; p1, const path&amp; p2, error_code ec);

        filesystem_error&amp; filesystem_error(const filesystem_error&amp;);
       ~filesystem_error();

        filesystem_error&amp; operator=(const filesystem_error&amp;);

        const path&amp; <a href="#filesystem_error-path1">path1</a>() const;
        const path&amp; <a href="#filesystem_error-path2">path2</a>() const;

        const char * <a href="#filesystem_error-what">what</a>() const;
      };
    } // namespace filesystem
  }} // namespaces std and tr2</pre>
  
<p>The class template <code>basic_filesystem_error</code> defines the type of 
objects thrown as exceptions to report file system errors from functions described in this 
clause.</p>
<h4> <a name="filesystem_error-members"> <code>filesystem_error</code> members</a></h4>
  
<pre><a name="filesystem_error-2-arg">filesystem_error</a>(const string&amp; what_arg, error_code ec);</pre>
  
<blockquote>
  <p><i>Postcondition:</i></p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="46%">
    <tr>
      <td width="18%">
      <p><b>Expression</b></td>
      <td width="82%">
      <p><b>Value</b></td>
    </tr>
    <tr>
      <td width="18%" bgcolor="#FFFFFF">
      <p><code>
      runtime_error::what()</code></td>
      <td width="82%" bgcolor="#FFFFFF">
      <p>
      <code><i>what_arg</i>.c_str()</code></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>code()</code></td>
      <td width="82%">
      <p><code>ec</code></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>path1().empty()</code></td>
      <td width="82%">
      <p><code>true</code></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>path2().empty()</code></td>
      <td width="82%">
      <p><code>true</code></td>
    </tr>
  </table>
</blockquote>
  
<pre><a name="filesystem_error-3-arg">filesystem_error</a>(const string&amp; what_arg, const path_type&amp; p1, error_code ec);</pre>
  
<blockquote>
  <p><i>Postcondition:</i></p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="46%">
    <tr>
      <td width="18%">
      <p><b>Expression</b></td>
      <td width="82%">
      <p><b>Value</b></td>
    </tr>
    <tr>
      <td width="18%" valign="top">
      <p><code>
      runtime_error::what()</code></td>
      <td width="82%">
      <p>
      <code><i>what_arg</i>.c_str()</code></td>
    </tr>
    <tr>
      <td width="18%" valign="top">
      <p><code>code()</code></td>
      <td width="82%">
      <p><code>ec</code></td>
    </tr>
    <tr>
      <td width="18%" valign="top">
      <p><code>path1()</code></td>
      <td width="82%">
      <p>Reference to stored copy of
       <code>p1</code></td>
    </tr>
    <tr>
      <td width="18%" valign="top">
      <p><code>path2().empty()</code></td>
      <td width="82%">
      <p><code>true</code></td>
    </tr>
  </table>
</blockquote>
  
<pre><a name="filesystem_error-4-arg">filesystem_error</a>(const string&amp; what_arg, const path_type&amp; p1, const path_type&amp; p2, error_code ec);</pre>
  
<blockquote>
  <p><i>Postcondition:</i></p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="46%">
    <tr>
      <td width="18%">
      <p><b>Expression</b></td>
      <td width="82%">
      <p><b>Value</b></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>
      runtime_error::what()</code></td>
      <td width="82%">
      <p>
      <u>
      <code><i>w</i></code></u><code><i>hat_arg</i>.c_str()</code></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>code()</code></td>
      <td width="82%">
      <p><code>ec</code></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>path1()</code></td>
      <td width="82%">
      <p>Reference to stored copy of
       <code>p1</code></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>path2()</code></td>
      <td width="82%">
      <p>Reference to stored copy of
       <code>p2</code></td>
    </tr>
  </table>
</blockquote>
  
<pre>const path&amp; <a name="filesystem_error-path1">path1</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> Reference to copy of <code>p1</code> stored by the 
  constructor, or, if none, an empty path.</p>
</blockquote>
  
<pre>const path&amp; <a name="filesystem_error-path2">path2</a>() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> Reference to copy of <code>p2</code> stored by the 
  constructor, or, if none, an empty path.</p>
</blockquote>
  
<pre>const char* <a name="filesystem_error-what">what</a>() const;</pre>
  
<blockquote>
  <p><i>Returns: </i>A string containing <code>runtime_error::what()</code>. The exact format is unspecified. 
  Implementations are encouraged but not required to include <code>
  path1.native_string()</code>if not empty, <code>path2.native_string()</code>if 
  not empty, and <code>system_error::what()</code> strings in the returned 
  string.</p>
</blockquote>
<h3><a name="Class-directory_entry">Class <code>directory_entry</code></a></h3>
  
<pre>  namespace std { namespace tr2 {
  {
    namespace filesystem
    {
      class directory_entry
      {
      public:

        // <a href="#directory_entry-constructors">constructors</a> and destructor
        directory_entry();
        directory_entry(const directory_entry&amp;);
        explicit directory_entry(const path_type&amp; p, file_status st=file_status(), file_status symlink_st=file_status());
       ~directory_entry(); 

        // <a href="#directory_entry-modifiers">modifiers</a>
        directory_entry&amp; operator=(const directory_entry&amp;);
        void assign(const path_type&amp; p, file_status st=file_status(), file_status symlink_st=file_status());
        void replace_filename(const path&amp; p, file_status st=file_status(), file_status symlink_st=file_status());

        // <a href="#directory_entry-observers">observers</a>
        const path&amp;  path() const;
        file_status  status() const;
        file_status  status(error_code&amp; ec) const;
        file_status  symlink_status() const;
        file_status  symlink_status(error_code&amp; ec) const;

        bool operator&lt; (const directory_entry&amp; rhs);
        bool operator==(const directory_entry&amp; rhs); 
        bool operator!=(const directory_entry&amp; rhs); 
        bool operator&lt; (const directory_entry&amp; rhs);
        bool operator&lt;=(const directory_entry&amp; rhs);
        bool operator&gt; (const directory_entry&amp; rhs);
        bool operator&gt;=(const directory_entry&amp; rhs);

      private:
        path_type            m_path;           // for exposition only
        mutable file_status  m_status;         // for exposition only; stat()-like
        mutable file_status  m_symlink_status; // for exposition only; lstat()-like
      };

    } // namespace filesystem
  }} // namespaces std and tr2</pre>
  
<p>A <code>directory_entry</code> object stores a <code>path object</code>, 
a <code>file_status</code> object for non-symbolic link status, and a <code>
file_status</code> object for symbolic link status. The <code>file_status</code> 
objects act as value caches.</p>
<blockquote>
<p>[<i>Note:</i> Because <code>status()</code>on a pathname may be a very expensive operation, 
some operating systems provide status information as a byproduct of directory 
iteration. Caching such status information can result is significant time savings. Cached and 
non-cached results may differ in the presence of race conditions. <i>-- end note</i>]</p>
<p><span style="background-color: #E0E0E0"><i>Actual cold-boot timing of iteration over 
a directory with 15,047 entries was six seconds for non-cached status queries 
versus one second for cached status queries. Windows XP, 3.0 GHz processor, with 
a moderately fast hard-drive. Similar speedups are expected on Linux and BSD-derived 
systems that provide status as a by-product of directory iteration.</i></span></p>
</blockquote>
<h4> <a name="directory_entry-constructors"> <code>directory_entry </code>constructors</a></h4>
  
<pre>directory_entry();</pre>
  
<blockquote>
  <p><i>Postcondition:</i></p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="36%">
    <tr>
      <td width="18%">
      <p><b>Expression</b></td>
      <td width="82%">
      <p><b>Value</b></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>path().empty()</code></td>
      <td width="82%">
      <p><code>true</code></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>status()</code></td>
      <td width="82%">
      <p><code>file_status()</code></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>symlink_status()</code></td>
      <td width="82%">
      <p><code>file_status()</code></td>
    </tr>
  </table>
</blockquote>
  
<pre>explicit directory_entry(const path_type&amp; p, file_status st=file_status(), file_status symlink_st=file_status());</pre>
  
<blockquote>
  <p><i>Postcondition:</i></p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="36%">
    <tr>
      <td width="18%">
      <p><b>Expression</b></td>
      <td width="82%">
      <p><b>Value</b></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>path()</code></td>
      <td width="82%">
      <p><code>p</code></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>status()</code></td>
      <td width="82%">
      <p><code>st</code></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>symlink_status()</code></td>
      <td width="82%">
      <p><code>symlink_st</code></td>
    </tr>
  </table>
</blockquote>
<h4> <a name="directory_entry-modifiers"> <code>directory_entry </code>modifiers</a></h4>
  
<pre>void assign(const path_type&amp; p, file_status st=file_status(), file_status symlink_st=file_status());</pre>
  
<blockquote>
  <p><i>Postcondition:</i></p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="36%">
    <tr>
      <td width="18%">
      <p><b>Expression</b></td>
      <td width="82%">
      <p><b>Value</b></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>path()</code></td>
      <td width="82%">
      <p><code>p</code></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>status()</code></td>
      <td width="82%">
      <p><code>st</code></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>symlink_status()</code></td>
      <td width="82%">
      <p><code>symlink_st</code></td>
    </tr>
  </table>
</blockquote>
  
<pre>void replace_filename(const path&amp; p, file_status st=file_status(), file_status symlink_st=file_status());</pre>
  
<blockquote>
  <p><i>Postcondition:</i></p>
  <table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="43%">
    <tr>
      <td width="18%">
      <p><b>Expression</b></td>
      <td width="82%">
      <p><b>Value</b></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>path()</code></td>
      <td width="82%">
      <p><code>path().branch() / s</code></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>status()</code></td>
      <td width="82%">
      <p><code>st</code></td>
    </tr>
    <tr>
      <td width="18%">
      <p><code>symlink_status()</code></td>
      <td width="82%">
      <p><code>symlink_st</code></td>
    </tr>
  </table>
</blockquote>
<h4> <a name="directory_entry-observers"> <code>directory_entry</code> observers</a></h4>
  
<pre>const path&amp; path() const;</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>m_path</code></p>
</blockquote>
  
<pre>file_status status() const;
file_status status(error_code&amp; ec) const;</pre>
  
<blockquote>
<p><i>Effects:</i> 
As if,</p>
  <blockquote>
    
    <pre>if ( !status_known( m_status ) )
{
  if ( status_known(m_symlink_status) &amp;&amp; !is_symlink(m_symlink_status) )
    { m_status = m_symlink_status; }
  else { m_status = status(m_path<i>[, ec]</i>); }
}</pre>
    
  </blockquote>
  <p><i>Returns:</i> <code>m_status</code></p>
  
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
  
</blockquote>
  
<pre>file_status  symlink_status() const;
file_status  symlink_status(error_code&amp; ec) const;</pre>
  
<blockquote>
<p><i>Effects:</i> 
As if,</p>
  <blockquote>
    
    <pre>if ( !status_known( m_symlink_status ) )
{
  m_symlink_status = symlink_status(m_path<i>[, ec]</i>);
}</pre>
    
  </blockquote>
  <p><i>Returns:</i> <code>
  m_symlink_status</code></p>
  
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
  
</blockquote>
  
<pre>bool operator==(const directory_entry&amp; rhs);</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>m_path == 
  rhs.m_path</code>.</p>
</blockquote>
  
<pre>bool operator!=(const directory_entry&amp; rhs);</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>m_path != 
  rhs.m_path</code>.</p>
</blockquote>
  
<pre>bool operator&lt; (const directory_entry&amp; rhs);</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>m_path &lt; 
  rhs.m_path</code>.</p>
</blockquote>
  
<pre>bool operator&lt;=(const directory_entry&amp; rhs);</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>m_path &lt;= 
  rhs.m_path</code>.</p>
</blockquote>
  
<pre>bool operator&gt; (const directory_entry&amp; rhs);</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>m_path &gt; 
  rhs.m_path</code>.</p>
</blockquote>
  
<pre>bool operator&gt;=(const directory_entry&amp; rhs);</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>m_path &gt;= 
  rhs.m_path</code>.</p>
</blockquote>
<h3><a name="Class-directory_iterator">Class <code>directory_iterator</code></a></h3>
<p>Objects of type <code>directory_iterator</code> provide standard library 
compliant iteration over the contents of a directory. Also see class <code>
<a href="#Class-recursive_directory_iterator">recursive_directory_iterator</a></code>.</p>
  
<pre>  namespace std { namespace tr2 {
  {
    namespace filesystem
    {
      class directory_iterator
        : public boost::iterator_facade&lt; directory_iterator,
                                         <a href="#Class-directory_entry">directory_entry</a>,
                                         boost::single_pass_traversal_tag &gt;
      {
      public:
        // <a href="#directory_iterator-members">member functions</a>

        directory_iterator();  // creates the &quot;end&quot; iterator
        directory_iterator(const directory_iterator&amp;);
        explicit directory_iterator(const path&amp; p);
        directory_iterator(const path&amp; p, error_code&amp; ec);
       ~directory_iterator();

        directory_iterator&amp; operator=(const directory_iterator&amp;);

        directory_iterator&amp; operator++();
        directory_iterator&amp; increment(error_code&amp; ec);

        // other members as required by
        //  C++ Std, 24.1.1 Input iterators [input.iterators]
      };

    } // namespace filesystem
  }} // namespaces std and tr2</pre>
  
<p> <code>directory_iterator</code> satisfies the requirements of an 
input iterator (C++ Std, 24.2.1, Input iterators [input.iterators]).</p>
<p>A <code>directory_iterator</code> reads successive elements from the directory for 
which it was constructed, as if by calling <i>POSIX</i>
<code>
<a href="http://www.opengroup.org/onlinepubs/000095399/functions/readdir_r.html">readdir_r()</a></code>. After a <code>directory_iterator</code> is constructed, and every time 
<code>operator++</code> is called, 
it reads a directory element and stores information about it in a object of type <code>
<a href="#Class-directory_entry">directory_entry</a></code>. 
<code>operator++</code> is not equality preserving; that is, <code>i == j</code> does not imply that
<code>++i == ++j</code>. </p>
<blockquote>
<p>[<i>Note:</i> The practical consequence of not preserving equality is that directory iterators 
can only be used for single-pass algorithms. <i>--end note</i>]</p>
</blockquote>
<p>If the end of the directory elements is reached, the iterator becomes equal to 
the end iterator value. The constructor <code>directory_iterator()</code> 
with no arguments always constructs an end iterator object, which is the only 
legitimate iterator to be used for the end condition. The result of <code>
operator*</code> on an end iterator is not defined. For any other iterator value 
a <code>const directory_entry&amp;</code> is returned. The result of
<code>operator-&gt;</code> on an end iterator is not defined. For any other iterator value a <code>const directory_entry*</code> is 
returned. </p>
<p>Two end iterators are always equal. An end iterator is not equal to a non-end 
iterator.</p>
<blockquote>
<p><i><span style="background-color: #E0E0E0">The above wording is based on the 
Standard Library's istream_iterator wording.</span></i></p>
</blockquote>
<p>The result of calling the <code>path()</code> member of the <code>
directory_entry</code> object obtained by dereferencing a <code>
directory_iterator</code> is a reference to a <code>path</code> 
object composed of the directory argument from which the iterator was 
constructed with filename of the directory entry appended as if by <code>
operator/=</code>. </p>
<p>Directory iteration shall not yield directory entries for the current (<i>dot</i>) 
and parent (<i>dot dot</i>) directories.</p>
<p>The order of directory entries obtained by dereferencing successive 
increments of a <code>directory_iterator</code> is unspecified.</p>
<blockquote>
<p>[<i>Note:</i> Programs performing directory iteration may wish to test if the 
path obtained by dereferencing a directory iterator actually exists. It could be 
a
symbolic link to a non-existent file. Programs recursively 
walking directory trees for purposes of removing and renaming entries may wish 
to avoid following symbolic links.</p>
<p>If a file  is removed from or added to a directory after the 
construction of a <code>directory_iterator</code> for the directory, it is 
unspecified whether or not subsequent incrementing of the iterator will ever 
result in an iterator whose value is the removed or added directory entry. See
<i>POSIX</i>
<code>
<a href="http://www.opengroup.org/onlinepubs/000095399/functions/readdir_r.html">readdir_r()</a></code>. <i>
--end note</i>]</p>
</blockquote>
<h4><a name="directory_iterator-members"><code>directory_iterator</code> members</a></h4>

<p><code><a name="directory_iterator-default-ctor">directory_iterator</a>();</code></p>

<blockquote>

<p><i>Effects:</i> Constructs the end iterator.</p>

<p><i>Throws:</i> Nothing.</p>

</blockquote>

  

<pre><code>explicit <a name="directory_iterator-ctor-path">directory_iterator</a>(</code>const path&amp; p<code>);
directory_iterator(</code>const path&amp; p, error_code&amp; ec<code>);</code></pre>
  
<blockquote>

<p><i>Effects:</i> Constructs a iterator representing the first 
entry in the directory <code>p</code> resolves to, if any; otherwise, the end iterator.</p>

<p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>

<p>[<i>Note:</i> To iterate over the current directory, use <code>
directory_iterator(&quot;.&quot;)</code> rather than <code>directory_iterator(&quot;&quot;)</code>.
<i>-- end note</i>]</p>
</blockquote>
  
<pre>directory_iterator&amp; <a name="directory_iterator-increment">operator++</a>();
directory_iterator&amp; increment(error_code&amp; ec);</pre>
  
<blockquote>

<p><i>Effects:</i> As specified by the C++ Standard, 24.1.1 Input iterators [input.iterators]</p>

<p><i>Returns:</i> <code>*this</code>.</p>

<p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>

</blockquote>
<h3><a name="Class-recursive_directory_iterator">Class <code>recursive_directory_iterator</code></a></h3>
<p>Objects of type <code>recursive_directory_iterator</code> provide standard library 
compliant iteration over the contents of a directory, including recursion into 
its sub-directories.</p>
  
<pre>  namespace std { namespace tr2 {
  {
    namespace filesystem
    {
      class recursive_directory_iterator :
        public iterator&lt;input_iterator_tag, directory_entry&gt;
      {
      public:

        // constructors and destructor
        recursive_directory_iterator();
        recursive_directory_iterator(const recursive_directory_iterator&amp;);
        explicit recursive_directory_iterator(const path&amp; p, <a href="#symlink_option">symlink_option</a> opt = symlink_option::none);
        recursive_directory_iterator(const path&amp; p, <a href="#symlink_option">symlink_option</a> opt, error_code&amp; ec);
        recursive_directory_iterator(const path&amp; p, error_code&amp; ec);
       ~recursive_directory_iterator();

        // observers
        int level() const;
        bool no_push<code>_pending</code>() const;

        // modifiers
        recursive_directory_iterator&amp; operator=(const recursive_directory_iterator&amp;);

        recursive_directory_iterator&amp; operator++();
        recursive_directory_iterator&amp; increment(error_code&amp; ec);

        void pop();
        void no_push(bool value=true);

        // other members as required by
        //  C++ Std, 24.1.2 Input iterators [input.iterators]

      private:
<i><b>        // actual data members may be stored in a shared pimpl object, or some
        // similar mechanism, to achieve the required input iterator copy semantics
</b></i>        int  m_level; <b><i>                                // for exposition only</i></b>
        bool m_no_<code>push</code>;  <i><b>                             // for exposition only
        </b></i><a href="#symlink_option">symlink_option</a> m_options;  <i><b>                   // for exposition only</b></i>
      };

    } // namespace filesystem
  }} // namespaces std and tr2</pre>

  

<p>The behavior of a <code>recursive_directory_iterator</code> is the same 
as a <code>directory_iterator</code> unless otherwise specified.</p>
<ul>
  <li>
  <p>Incrementing a <code>recursive_directory_iterator</code> pointing to a 
  directory causes that directory itself to be iterated ovee, as specified by 
  the <code>operator++</code> and <code>increment</code> functions.<br>
&nbsp;</li>
  <li>
  <p>When a <code>recursive_directory_iterator</code> reaches the end of the directory currently being iterated 
  over, or when <code>pop()</code> is called, <code>m_level</code> is 
  decremented, and iteration of the parent directory continues.</li>
</ul>
  
<pre>recursive_directory_iterator();</pre>
  
<blockquote>

<p><i>Effects:</i> Constructs the end iterator.</p>

<p><i>Throws:</i> Nothing.</p>

</blockquote>

  

<pre>explicit recursive_directory_iterator(const path&amp; p, <a href="#symlink_option">symlink_option</a> opt = symlink_option::none);
recursive_directory_iterator(const path&amp; p, <a href="#symlink_option">symlink_option</a> opt, error_code&amp; ec);
recursive_<code>directory_iterator(</code>const path&amp; p, error_code&amp; ec<code>);</code></pre>
  
<blockquote>

<p><i>Effects:</i>&nbsp; Constructs a iterator representing the first 
entry in the directory <code>p</code> resolves to, if any; otherwise, the end iterator.</p>

<p><i>Postcondition: </i>Unless the end iterator was constructed,<i> </i>
<code>level() == 0 &amp;&amp; no_push_pending() == false &amp;&amp; m_options == opt</code>. 
For the signature without a <code>symlink_option</code> argument, <code>opt</code> 
is assumed to be <code>symlink_option::none</code>.</p>

<p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>

<p>[<i>Note:</i> To iterate over the current directory, use <code>recursive_directory_iterator(&quot;.&quot;)</code> rather than
<code>recursive_directory_iterator(&quot;&quot;)</code>.
<i>-- end note</i>]</p>

<p>[<i>Note:</i> By default, <code>recursive_directory_iterator</code> does not 
follow directory symlinks. To follow directory symlinks, specify <code>opt</code> 
as <code>symlink_option::recurse</code>
<i>-- end note</i>]</p>
</blockquote>
  
<pre>int level() const;</pre>
  
<blockquote>
  <p><i>Requires:</i> <code>*this != recursive_directory_iterator()</code>.</p>
  <p><i>Returns:</i> <code>m_level</code>.</p>
  <p><i>Throws:</i> Nothing.</p>
</blockquote>
  
<pre>bool <code>no_push_pending</code>() const;</pre>
  
<blockquote>
  <p><i>Requires:</i> <code>*this != recursive_directory_iterator()</code>.</p>
  <p><i>Returns:</i> <code>m_no_push</code>.</p>
  <p><i>Throws:</i> Nothing.</p>
</blockquote>
  
<pre><code>recursive_directory_iterator</code>&amp; <a name="recursive_directory_iterator-increment">operator++</a>();
recursive_directory_iterator&amp; increment(error_code&amp; ec);</pre>
  
<blockquote>

<p><i>Effects:</i> As specified by the C++ Standard, 24.1.1 Input iterators [input.iterators], 
except:</p>

<ul>
  <li>

<p>if <code>!no_push_pending() &amp;&amp; is_directory(this-&gt;status()) 
&amp;&amp; (!is_symlink(this-&gt;symlink_status()) || (m_options 
&amp; symlink_option::recurse) != 0)</code> then&nbsp; <code>m_level</code> 
is incremented and directory <code>(*this)-&gt;path()</code> is recursively iterated into.<br>
&nbsp;</p>

  </li>
  <li>
  <p>if there are no more directory entries at this level then <code>m_level</code> 
is decremented and iteration of the parent directory resumes.</li>
</ul>

<p><i>Postcondition:</i> <code>no_push_pending() == false</code>.</p>

<p><i>Returns:</i> <code>*this</code>.</p>

<p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>

</blockquote>
  
<pre>void pop();</pre>
  
<blockquote>
  <p><i>Requires:</i> <code>*this != recursive_directory_iterator()</code>.</p>
  <p><i>Effects:</i> If <code>level() == 0</code>, set <code>*this</code> to <code>recursive_directory_iterator()</code>. 
  Otherwise, <code>--m_level</code>, cease iteration of the directory currently being 
  iterated over, and continue iteration over the parent directory.</p>
  <p><i>Throws:</i> Nothing.</p>
</blockquote>
  
<pre>void no_push(bool value=true);</pre>
  
<blockquote>
  <p><i>Requires:</i> <code>*this != recursive_directory_iterator()</code>.</p>
<p><i>Postcondition:</i> <code>no_push_pending() == value</code>.</p>
  <p><i>Throws:</i> Nothing.</p>
  <p>[<i>Note:</i> <code>no_push()</code> is used to prevent 
  unwanted recursion into a directory. <i>--end note</i>]</p>
</blockquote>
<h3><a name="file_status">Class file_status</a></h3>
  
<pre>  namespace std { namespace tr2 {
  {
    namespace filesystem
    {
      class file_status
      {
      public:
        file_status();
        file_status(const file_status&amp;);
        explicit file_status(file_type v=status_error);
       ~file_status();

        <a href="#file_type">file_type</a> type() const;
        void type(file_type v);
      };
    } // namespace filesystem
  } // namespace std { namespace tr2 {</pre>
  
<p>An object of type <code>file_status</code> stores information about the status of a 
file. The internal form of the stored information is unspecified.</p>
<blockquote>
  <p><i>[Note: </i>The class may be extended in the future to store 
  additional status information. <i>--end note]</i></p>
</blockquote>
<h4>Members</h4>
  
<pre>explicit file_status(<a href="#file_type">file_type</a> v=status_error);</pre>
  
<blockquote>
  <p><i>Effects:</i> Stores <code>v</code>.</p>
  <p><i>Throws:</i> Nothing.</p>
</blockquote>
  
<pre>file_type type() const;</pre>
  
<blockquote>
  <p><i>Returns: </i>The stored <a href="#file_type"> <code>file_type</code>.</a></p>
</blockquote>
  
<pre>void type(<a href="#file_type">file_type</a> v);</pre>
  
<blockquote>
  <p><i>Effects:</i> Stores <code>v</code>, replacing the previously stored 
  value.</p>
</blockquote>
<h3><a name="Operational-functions">Operational functions</a></h3>
<p>Operational functions query or modify files, including directories, in external 
storage.</p>
<p style="font-size: 10pt">Operational functions access a file by resolving an 
object of class <code>path</code> to a particular file in a file hierarchy. The 
path is resolved as if by the <i>POSIX</i>
<a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/xbd_chap04.html#tag_04_11">
Pathname Resolution</a> mechanism.</p>
<p>[<i>Note: </i>Because hardware failures, network failures,
<a href="#Race-condition">race conditions</a>, and many 
other kinds of errors occur frequently in file system operations, users should be aware 
that any filesystem operational function, no matter how apparently innocuous, may encounter 
an error.&nbsp;See <a href="#Error-reporting">Error reporting</a>. <i>-- end note</i>]</p>
<h4><a name="Function-specifications">Operational function specifications</a></h4>
  
<pre>path <a name="absolute">absolute</a>(const path&amp; p, const path&amp; base=current_path());</pre>
  
  <blockquote>
  <p><i>Returns:</i> A path composed according to to the 
  following table</p>
  <table border="1" cellpadding="5" cellspacing="0" bordercolor="#111111" style="border-collapse: collapse">
    <tr>
      <td align="center">
      <p>&nbsp;</td>
      <td align="center">
      <p><b><code>p.has_root_directory()</code></b></td>
      <td align="center">
      <p><b><code>!p.has_root_directory()</code></b></td>
    </tr>
    <tr>
      <td align="center">
      <p><b><code>p.has_root_name()</code></b></td>
      <td align="center">
      <p><code>return p</code></td>
      <td align="center">
      <p><code>return p.root_name() / 
      absolute(base).root_directory()<br>
      / absolute(base).relative_path() / p.relative_path()</code></td>
    </tr>
    <tr>
      <td align="center">
      <p><b><code>!p.has_root_name()</code></b></td>
      <td align="center">
      <p><code>return absolute(base).root_name()<br>
      / p</code></td>
      <td align="center">
      <p><code>return absolute(base) / p</code></td>
    </tr>
  </table>
  <p><i>Postcondition:</i> For the returned path, <code>rp,</code> <code>
  rp.is_absolute()</code> is true.</p>
  <p><i>Throws:</i> If <code>base.is_absolute()</code> is true, throws only if 
  memory allocation fails.</p>
</blockquote>
  
<pre>void <a name="copy">copy</a>(const path&amp; from, const path&amp; to);
void copy(const path&amp; from, const path&amp; to, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Effects:</i> As if</p>
  
  <blockquote>
    
    <pre>file_status s(symlink_status(from<i>[</i><code>, ec</code><i>]</i>));
if(is_symlink(s))
  copy_symlink(from, to<i>[</i><code>, ec</code><i>]</i>);
else if(is_directory(s))
  copy_directory(from, to<i>[</i><code>, ec</code><i>]</i>);
else if(is_regular_file(s))
  copy_file(from, to, copy_option::fail_if_exists<i>[</i><code>, ec</code><i>]</i>);
else
<i> Report error as specified in <a href="#Error-reporting">Error reporting</a>.</i></pre>
    
  </blockquote>
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
  
</blockquote>
  
<pre>void <a name="copy_directory">copy_directory</a>(const path&amp; from, const path&amp; to);
void copy_directory(const path&amp; from, const path&amp; to, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Effects: </i></p>
  
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
  
</blockquote>
  
<pre>void copy_file(const path&amp; from, const path&amp; to);
void copy_file(const path&amp; from, const path&amp; to, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Effects: </i><code>copy_file(from, to, 
  copy_option::fail_if_exists</code><i>[</i><code>, ec</code><i>]</i><code>)</code>.</p>
  
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
  
</blockquote>
  
<pre>void <a name="copy_file">copy_file</a>(const path&amp; from, const path&amp; to, <a href="#copy_option">copy_option</a> option);
void <a name="copy_file2">copy_file</a>(const path&amp; from, const path&amp; to, <a href="#copy_option">copy_option</a> option, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Effects:</i> If <code>option == copy_option::</code><code>fail_if_exists 
  &amp;&amp; exists(to)</code>, an error is reported. Otherwise, the contents and attributes of the file <code>from</code> 
  resolves to are copied to the file <code>to</code> resolves to.</p>
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
</blockquote>
  
<pre>void <a name="copy_symlink">copy_symlink</a>(const path&amp; existing_symlink, const path&amp; new_symlink);
void copy_symlink(const path&amp; existing_symlink, const path&amp; new_symlink, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Effects: </i><code>create_symlink(read_symlink(existing_symlink</code><i>[</i><code>, ec</code><i>]</i><code>), 
  new_symlink</code><i>[</i><code>, ec</code><i>]</i><code>)</code>.</p>
  
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
  
</blockquote>
  
<pre>bool <a name="create_directories">create_directories</a>(const path&amp; p);
bool <a name="create_directories2">create_directories</a>(const path&amp; p, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Requires:</i> <code>p.empty() || <br>
  forall px: px == p || is_parent(px, p): is_directory(px) || !exists( px )</code>
  </p>
  <p><i>Postcondition:</i> <code>is_directory(p)</code></p>
  <p><i>Returns:</i> The value of <code>!exists(p)</code> prior to the 
  establishment of the postcondition.</p>
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
</blockquote>
  
<pre>bool <a name="create_directory">create_directory</a>(const path&amp; p);
bool <a name="create_directory2">create_directory</a>(const path&amp; p, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Effects:</i> Attempts to create the directory <code>p</code> resolves to, 
  as if by<i> POSIX </i><code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/mkdir.html">mkdir()</a></code> with a second argument of S_IRWXU|S_IRWXG|S_IRWXO. </p>
  <p><i>Postcondition:</i> <code>is_directory(p)</code></p>
  <p><i>Returns:</i> <code>true</code> if a new directory was created, otherwise 
  <code>false</code>.</p>
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
</blockquote>
  
<pre>void <a name="create_directory_symlink">create_directory_symlink</a>(const path&amp; to, const path&amp; new_symlink);
void create_directory_symlink(const path&amp; to, const path&amp; new_symlink, error_code&amp; ec);</pre>
  
<blockquote style="font-size: 10pt">
  <p style="font-size: 10pt"><i>Effects:</i> 
  Establishes the postcondition, as if by <i>
  POSIX</i>
  <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/symlink.html">
  symlink()</a></code>.</p>
  <p style="font-size: 10pt"><i>
  Postcondition:</i> <code>new_symlink</code> resolves to a symbolic link file that 
  contains an unspecified representation of <code>to</code>.</p>
  <p style="font-size: 10pt"><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
  <p style="font-size: 10pt">[<i>Note:</i> 
  Some <b>operating systems</b>, such as Windows, require symlink creation to 
  identify that the link is to a directory. Portable code should use <code>
  create_directory_symlink()</code> to create directory symlinks rather than
  <code>create_symlink()</code>  <i>-- end note</i>]</p>
  <p>[<i>Note:</i> 
  Some <b>operating systems</b> do not support symbolic links at all or support 
  them only for regular files. Windows prior to Vista, for example, did not 
  support symbolic links. 
  Some <b>file systems</b> do not 
  support 
  symbolic links regardless of the operating system - the FAT system used on floppy discs, memory cards and flash 
  drives, 
  for example. Thus symbolic links should only be used if these situations are 
  not concerns, or if workarounds are provided.  <i>-- end note</i>]</p>
  </blockquote>
  
<pre>void <a name="create_hard_link">create_hard_link</a>(const path&amp; to, const path&amp; new_hard_link);
void <a name="create_hard_link2">create_hard_link</a>(const path&amp; to, const path&amp; new_hard_link, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Effects:</i> Establishes the postcondition, as if by
   <i>POSIX</i>
   <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/link.html">
  link()</a></code>.</p>
  <p><i>Postcondition:</i></p>
  <ul>
    <li>
    <p>&nbsp;<code>exists(to) &amp;&amp; 
    exists(</code><code>new_hard_link</code><code>) &amp;&amp; equivalent(to, 
     
    </code><code>new_hard_link</code><code>)</code></li>
    <li>
    <p>The contents of the file or directory
    <code>to</code> resolves to are unchanged.</li>
  </ul>
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
  <p>[<i>Note:</i> 
  Some <b>operating systems</b> do not support hard links at all or support 
  them only for regular files. Some <b>file systems</b> do not support hard 
  links regardless of the operating system - the FAT system used on floppy 
  discs, memory cards and flash drives, for example. Some file systems limit the 
  number of links per file. Thus hard links should only be used if these 
  situations are not concerns, or if workarounds are provided.  <i>-- end note</i>]</p>
  </blockquote>
  
<pre>void <a name="create_symlink">create_symlink</a>(const path&amp; to, const path&amp; new_symlink);
void <a name="create_symlink2">create_symlink</a>(const path&amp; to, const path&amp; new_symlink, error_code&amp; ec);</pre>
  
<blockquote style="font-size: 10pt">
  <p style="font-size: 10pt"><i>Effects:</i> 
  Establishes the postcondition, as if by <i>
  POSIX</i>
  <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/symlink.html">
  symlink()</a></code>.</p>
  <p style="font-size: 10pt"><i>
  Postcondition:</i> <code>new_symlink</code> resolves to a symbolic link file that 
  contains an unspecified representation of <code>to</code>.</p>
  <p style="font-size: 10pt"><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
  <p>[<i>Note:</i> 
  Some <b>operating systems</b> do not support symbolic links at all or support 
  them only for regular files. Windows prior to Vista, for example, did not 
  support symbolic links. 
  Some <b>file systems</b> do not 
  support 
  symbolic links regardless of the operating system - the FAT system used on floppy discs, memory cards and flash 
  drives, 
  for example. Thus symbolic links should only be used if these situations are 
  not concerns, or if workarounds are provided.  <i>-- end note</i>]</p>
  </blockquote>
  
<pre>path <a name="current_path">current_path</a>();
path <a name="current_path2">current_path</a>(error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Returns:</i> The current working directory path, as if by <i>POSIX</i>
  <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/getcwd.html">
  getcwd()</a></code>. <code>is_absolute()</code> is true for the returned path.</p>
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
  <p>[<i>Note: </i>The <code>
  current_path()</code> name was chosen to emphasize that the return is a 
  path, not just a single directory name.</p>
  <p>The current path as returned by many operating systems is a dangerous 
  global variable. It may be changed unexpectedly by a third-party or system 
  library functions, or by another thread.&nbsp; <i>-- end note</i>]</p>
</blockquote>
  
<pre>void current_path(const path&amp; p);
void current_path(const path&amp; p, error_code&amp; ec);</pre>
  
<blockquote>
  <p style="font-size: 10pt"><i>Effects:</i> 
  Establishes the postcondition, as if by <i>
  POSIX</i>
  <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/chdir.html">
  chdir()</a></code>.</p>
<p><i>Postcondition:</i> <code>equivalent(p, current_path())</code>.</p>
<p><i>Throws:</i> As specified in
<a href="#Error-reporting">
Error reporting</a>.</p>
  <p>[<i>Note: </i>The current path for many operating systems is a dangerous 
  global state. It may be changed unexpectedly by a third-party or system 
  library functions, or by another thread.&nbsp; <i>-- end note</i>]</p>
</blockquote>
  
<pre>bool <a name="exists">exists</a>(file_status s);</pre>
  
<blockquote>
  <p><i>Returns:</i>
  <code>status_known(s) &amp;&amp; s.type() != file_not_found</code></p>
  <p><i>Throws:</i> Nothing.</p>
</blockquote>
  
<pre>bool <a name="exists2">exists</a>(const path&amp; p);
bool <a name="exists3">exists</a>(const path&amp; p, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Returns:</i> <code>exists(status(p))</code> or <code>exists(status(p, ec))</code>, 
  respectively.</p>
<p><i>Throws:</i> <code>filesystem_error</code>; overload with <code>error_code&amp;</code> throws 
nothing.</p>
</blockquote>
  
<pre><code>bool <a name="equivalent">equivalent</a>(const path&amp; p1, const path&amp; p2);
bool <a name="equivalent2">equivalent</a>(const path&amp; p1, const path&amp; p2, error_code&amp; ec);</code></pre>
  
<blockquote style="font-size: 10pt">
  <p style="font-size: 10pt"><i>Effects:</i> Determines <code>file_status s1</code> 
  and <code>s2</code>, as if by <code>status(p1)</code> and&nbsp; <code>status(p2)</code>, 
  respectively.</p>
  <p style="font-size: 10pt"><i>Returns:</i> <code>true</code>, if <code>sf1 == 
  sf2</code> and <code>p1</code> and <code>p2</code> resolve to the same file 
  system entity, else <code>false</code>.</p>
  <blockquote>
  <p style="font-size: 10pt">Two paths are considered to resolve to the same 
  file system entity if two candidate entities reside on the same device at the 
  same location. This is determined as if by the values of the <i>POSIX</i>
  <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">
  stat</a></code> structure<code>,</code> obtained as if by <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/stat.html">
  stat()</a></code> for the two paths, having equal <code>st_dev</code> values 
  and equal <code>st_ino</code> values.</p>
  <p style="font-size: 10pt">[<i>Note:</i> <i>POSIX</i> requires that <i>&quot;st_dev</i> 
  must be unique within a Local Area Network&quot;. Conservative <i>POSIX</i> 
  implementations may also wish to check for equal <code>st_size</code> and
  <code>st_mtime</code> values. <i>Windows</i> implementations may use <code>
  GetFileInformationByHandle()</code> as a surrogate for <code>stat()</code>, 
  and consider &quot;same&quot; to be equal values for <code>dwVolumeSerialNumber</code>,
  <code>nFileIndexHigh</code>, <code>nFileIndexLow</code>, <code>nFileSizeHigh</code>,
  <code>nFileSizeLow</code>, <code>ftLastWriteTime.dwLowDateTime</code>, and
  <code>ftLastWriteTime.dwHighDateTime</code>. <i>-- end note</i>]</p>
  </blockquote>
  <p style="font-size: 10pt"><i>Throws:</i> <code>filesystem_error</code>
  if <code>(!exists(s1) &amp;&amp; !exists(s2)) || (is_other(s1) &amp;&amp; is_other(s2))</code>, 
  otherwise as specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
</blockquote>

<pre>uintmax_t <a name="file_size">file_size</a>(const path&amp; p);
uintmax_t <a name="file_size2">file_size</a>(const path&amp; p, error_code&amp; ec);</pre>

<blockquote>
  <p>Remarks: </p>
  <p><i>Returns:</i> If <code>exists(p) &amp;&amp; is_regular_file(p)</code>, the size 
  in bytes 
  of the file <code>p</code> resolves to, determined as if by the value of 
  the <i>POSIX</i> <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">stat</a></code> structure member <code>st_size</code> 
  obtained as if by <i>POSIX</i> <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/stat.html">stat()</a></code>. 
  Otherwise, <code>static_cast&lt;uintmax_t&gt;(-1)</code>.</p>
  <p style="font-size: 10pt"><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
</blockquote>
  
<pre>uintmax_t <a name="hard_link_count">hard_link_count</a>(const path&amp; p);
uintmax_t hard_link_count(const path&amp; p, error_code&amp; ec);</pre>
  
<blockquote>

  <p><i>Returns:</i> The number of hard links for <code>p</code>.</p>
  <p style="font-size: 10pt"><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>

</blockquote>

  

<pre>const path&amp; <a name="initial_path">initial_path</a>();
const path&amp; <a name="initial_path">initial_path</a><code>(error_code&amp; ec</code>);</pre>
  
<blockquote>
  <p><i>Returns:</i> 
  <code>current_path()</code> as of the first call to <code>initial_path()</code>.</p>
  <p>[<i>Note:</i> <code>
  initial_path()</code> is not thread safe, and may return an undesirable result 
  if called subsequent to a change to the current directory. These problems can 
  be avoided by calling <code>initial_path()</code> immediately on entry to 
  main().&nbsp; <i>--end note</i>]</p>
  <p><i>Throws:</i> For the first call, as specified in
  <a href="#Error-reporting">
  Error reporting</a>. Subsequent calls throw nothing.</p>
</blockquote>
  
<pre>bool <code><a name="is_directory">is_directory</a></code>(file_status s);</pre>
  
<blockquote>
  <p><i>Returns:</i> 
  <code>s.type() == directory_file</code></p>
  <p><i>Throws:</i> Nothing.</p>
</blockquote>
  
<pre><code>bool <a name="is_directory2">is_directory</a>(const path&amp; p);
bool <a name="is_directory3">is_directory</a>(const path&amp; p, error_code&amp; ec);</code></pre>
  
<blockquote>
  <p><i>Returns:</i> <code>is_directory(status(p))</code> or <code>is_directory(status(p, ec))</code>, 
  respectively.</p>
<p><i>Throws:</i> <code>filesystem_error</code>; overload with <code>error_code&amp;</code> throws 
nothing.</p>
</blockquote>
  
<pre><code>bool <a name="is_empty">is_empty</a>(const path&amp; p);
bool <a name="is_empty2">is_empty</a></a>(const path&amp; p, error_code&amp; ec);</code></pre>
  
<blockquote>
  <p><i>Effects:</i> Determines <code>file_status s</code>, as if by <code>
  status(p, ec)</code>.</p>
  <p><i>Returns:</i> <code>is_directory(s)<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ? 
  directory_iterator(p) == directory_iterator()<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; : file_size(p) == 0;</code></p>
</blockquote>
  
<pre>bool <code><a name="is_regular_file">is_regular_file</a></code>(file_status s);</pre>
  
<blockquote>
  <p><i>Returns:</i>
  <code>s.type() == regular_file</code></p>
  <p><i>Throws:</i> Nothing.</p>
</blockquote>
  
<pre><code>bool <a name="is_regular_file2">is_regular_file</a>(const path&amp; p);</code></pre>
  
<blockquote>
  <p><i>Returns:</i> <code>is_regular_file(status(p))</code>.</p>
  <p><i>Throws:</i> <code>filesystem_error</code> 
  if <code>status(p)</code> would throw <code>filesystem_error.</code></p>
  </blockquote>
  
<pre><code>bool <a name="is_regular_file3">is_regular_file</a>(const path&amp; p, error_code&amp; ec);</code></pre>
  
<blockquote>
  <p><i>Effects:</i> Sets <code>ec</code> as if by <code>status(p, ec)</code>. [<i>Note:</i>
      <code>status_error</code>,
      <code>file_not_found</code> 
  and
      <code>type_unknown</code> 
  cases set <code>ec</code> 
  to error values. To distinguish between cases, call the <code>
  status</code> 
  function directly. <i>-- end 
  note</i>] </p>
  <p><i>Returns:</i> <code>is_regular_file(status(p, ec))</code>.</p>
  <p><i>Throws:</i> Nothing.</p>
</blockquote>
  
<pre>bool <a name="is_other">is_other</a>(file_status s);</pre>
  
<blockquote>
  <p><i>Returns:</i>
  <code>return exists(s) &amp;&amp; !is_regular_file(s) &amp;&amp; !is_directory(s) &amp;&amp; !is_symlink(s)</code></p>
  <p><i>Throws:</i> Nothing.</p>
</blockquote>
  
<pre><code>bool <a name="is_other2">is_other</a>(const path&amp; p);
bool <a name="is_other3">is_other</a>(const path&amp; p, error_code&amp; ec);</code></pre>
  
<blockquote>
  <p><i>Returns:</i> <code>is_other(status(p))</code> or <code>is_other(status(p, ec))</code>, 
  respectively.</p>
  <p><i>Throws:</i> <code>filesystem_error</code>; overload with <code>error_code&amp;</code> throws 
  nothing.</p>
</blockquote>
  
<pre>bool <a name="is_symlink">is_symlink</a>(file_status s);</pre>
  
<blockquote>
  <p><i>Returns:</i> 
  <code>s.type() == symlink_file</code></p>
  <p><i>Throws:</i> Nothing.</p>
</blockquote>
  
<pre><code>bool <a name="is_symlink2">is_symlink</a>(const path&amp; p);
bool <a name="is_symlink3">is_symlink</a>(const path&amp; p, error_code&amp; ec);</code></pre>
  
<blockquote>
  <p><i>Returns:</i> <code>is_symlink(symlink_status(p))</code> or <code>is_symlink(symlink_status(p, ec))</code>, 
  respectively.</p>
  <p><i>Throws:</i> <code>filesystem_error</code>; overload with <code>error_code&amp;</code> throws 
  nothing.</p>
</blockquote>
  
<pre>time_t <a name="last_write_time">last_write_time</a>(const path&amp; p);
time_t <a name="last_write_time2">last_write_time</a>(const path&amp; p<code>, error_code&amp; ec</code>);</pre>
  
<blockquote>
  <p><i>Returns:</i> The time of last data modification of <code>p</code>, determined as if by the 
  value of the <i>POSIX</i> <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">stat</a></code> structure member <code>st_mtime</code>&nbsp; obtained 
  as if by <i>POSIX</i> <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/stat.html">stat()</a></code>.</p>
</blockquote>
  
<pre>void <a name="last_write_time3">last_write_time</a>(const path&amp; p, const time_t new_time);
void <a name="last_write_time4">last_write_time</a>(const path&amp; p, const time_t new_time<code>, error_code&amp; ec</code>);</pre>
  
<blockquote>
  <p><i>Effects:</i> Sets the time of last data modification of the file 
  resolved to by <code>p</code> 
  to <code>new_time</code>, as if by <i>POSIX</i> <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/stat.html">stat()</a></code> 
  followed by <i>POSIX</i>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/utime.html">
  <code>utime()</code></a>.</p>
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
  <p>[<i>Note:</i> A postcondition of <code>last_write_time(p) == 
  new_time</code> is not specified since it might not hold for file systems 
  with coarse time granularity. <i>-- end note</i>]</p>
</blockquote>
  
<pre>path <a name="read_symlink">read_symlink</a>(const path&amp; p);
path read_symlink(const path&amp; p, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Returns:</i>&nbsp; If <code>p</code> resolves to a symbolic 
  link, a <code>path</code> object containing the contents of that symbolic 
  link. Otherwise an empty <code>path</code> object.</p>
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>. [<i>Note:</i> It is an error if <code>p</code> does not 
  resolve to a symbolic link. <i>-- end note</i>]</p>
</blockquote>
  
<pre>bool <a name="remove">remove</a>(const path&amp; p);
bool <a name="remove2">remove</a>(const path&amp; p, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Effects:</i>&nbsp; If <code>exists(symlink_status(p,ec))</code>, it is 
  removed 
  as if by<i> POSIX </i><code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/remove.html">remove()</a></code>.</p>
  <blockquote>
  <p>[<i>Note:</i> A symbolic link is itself removed, rather than the file it 
  resolves to being removed. <i>-- end note</i>]</p>
  </blockquote>
  <p><i>Postcondition:</i> <code>!exists(symlink_status(p))</code>.</p>
  <p><i>Returns:</i>&nbsp; <code>false</code> if p did not exist in the first 
  place, otherwise <code>true</code>.</p>
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
</blockquote>
  
<pre>uintmax_t <a name="remove_all">remove_all</a>(const path&amp; p);
uintmax_t <a name="remove_all2">remove_all</a>(const path&amp; p, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Effects:</i>&nbsp; Recursively deletes the contents of p if it exists, 
  then deletes file <code>p</code> itself, 
  as if by<i> POSIX </i><code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/remove.html">remove()</a></code>.</p>
  <blockquote>
  <p>[<i>Note:</i> A symbolic link is itself removed, rather than the file it 
  resolves to being removed. <i>-- end note</i>]</p>
  </blockquote>
  <p><i>Postcondition:</i> <code>!exists(p)</code></p>
  <p><i>Returns:</i> The number of files removed.</p>
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
</blockquote>
  
<pre>void <a name="rename">rename</a>(const path&amp; old_p, const path&amp; new_p);
void <a name="rename2">rename</a>(const path&amp; old_p, const path&amp; new_p, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Effects:</i> Renames <code>old_p</code> to <code>new_p</code>, as if by
  <i>POSIX</i> <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/rename.html">
  rename()</a></code>.</p>
  <blockquote>
  <p>[<i>Note:</i> If <code>old_p</code> and <code>new_p</code> resolve to the 
  same existing file, no action is taken. Otherwise, if <code>new_p</code> resolves to an 
  existing non-directory file, it is removed, while if <code>new_p</code> resolves to an 
  existing directory, it is removed if empty on POSIX but is an error on Windows. A symbolic link is itself renamed, rather than 
  the file it resolves to being renamed. <i>-- end note</i>]</p>
  </blockquote>
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
</blockquote>
  
<pre>void <a name="resize_file">resize_file</a>(const path&amp; p, uintmax_t new_size);
void <a name="resize_file2">resize_file</a>(const path&amp; p, uintmax_t new_size, error_code&amp; ec);</pre>
  
<blockquote>
<p><i>Postcondition:</i> <code>file_size() == new_size</code>.</p>
<p><i>Throws:</i> As specified in
<a href="#Error-reporting">
Error reporting</a>.</p>
  <p style="font-size: 10pt"><i>Remarks:</i> Achieves its postconditions as if by 
  POSIX <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/truncate.html">
  truncate()</a></code>.</p>
</blockquote>
  
<pre>space_info <a name="space">space</a>(const path&amp; p);
space_info <a name="space2">space</a>(const path&amp; p, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Returns:</i> An object of type <code>
  <a href="#space_info">space_info</a></code>. The value of the <code>space_info</code> object is determined as if by 
  using  <i>POSIX</i> <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/statvfs.html" style="text-decoration: none">
  statvfs()</a></code> to obtain a <i>POSIX</i> struct <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/statvfs.h.html" style="text-decoration: none">
  statvfs</a></code>, and then multiplying its <code>f_blocks</code>, <code>
  f_bfree</code>, and <code>f_bavail</code> members by its <code>f_frsize</code> 
  member, and assigning the results to the <code>capacity</code>, <code>free</code>, 
  and <code>available</code> members respectively. Any members for which the 
  value cannot be determined shall be set to -1.</p>
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
</blockquote>
  
<pre><a href="#file_status">file_status</a> <a name="status">status</a>(const path&amp; p);</pre>
  
<blockquote>
  <p><i>Effects: </i>As if:</p>
  <blockquote>
    
    <pre>error_code ec;
file_status result = status(p, ec);
if (result == status_error)
  throw filesystem_error(<i>implementation-supplied-message</i>, p, ec);
return result;</pre>
    
  </blockquote>
  <p><i>Returns:</i> See above.</p>
  <p><i>Throws:</i> <code>filesystem_error</code>. 
[<i>Note:</i> <code>result</code> values of <code>
      file_status(file_not_found)</code>and <code>
      file_status(type_unknown)</code> are not considered failures and do not 
  cause an exception to be 
thrown.<i> -- end note</i>] </p>
  </blockquote>
  
<pre><a href="#file_status">file_status</a> <a name="status2">status</a>(const path&amp; p, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Effects: </i></p>
  <blockquote>
    <p>If possible, determines the attributes 
    of the file
    <code>p</code> resolves to, as if by<i> POSIX </i> <code>
  <a href="http://www.opengroup.org/onlinepubs/000095399/functions/stat.html">stat()</a></code>.</p>
      <p>If, during attribute determination, the underlying file system API reports 
    an error, sets <code>ec</code> to indicate the specific error reported. 
    Otherwise, <code>ec.clear()</code>.</p>
    <blockquote>
      <p>[<i>Note:</i> This allows users to inspect the specifics of underlying 
      API errors even when the value returned by <code>status()</code> is not <code>
      file_status(status_error)</code>.&nbsp; <i>--end note</i>]</p>
    </blockquote>
    </blockquote>
  <p><i>Returns:</i></p>
  <blockquote>
    <p>If <code>ec != error_code()</code>:</p>
    <ul>
      <li>
      <p>If the specific error indicates that <code>p</code> cannot be resolved 
      because some element of the path does not exist, return <code>
      file_status(file_not_found)</code>. [<i>Note:</i> POSIX errors that 
      indicate this are ENOENT or ENOTDIR. Windows equivalents 
      include ERROR_FILE_NOT_FOUND, ERROR_PATH_NOT_FOUND, ERROR_INVALID_NAME, 
      ERROR_INVALID_PARAMETER, ERROR_BAD_PATHNAME, and ERROR_BAD_NETPATH. <i>-- 
      end note</i>]<br>
&nbsp;</li>
      <li>
      <p>Otherwise, if the specific error indicates that <code>p</code> can be resolved 
      but the attributes cannot be determined, return <code>
      file_status(type_unknown)</code>. [<i>Note: </i>For example, Windows 
      ERROR_SHARING_VIOLATION errors. For POSIX, the case never arises. <i>-- end 
      note</i>]<br>
&nbsp;</li>
      <li>
      <p>Otherwise, return <code>
      file_status(status_error)</code>.</li>
    </ul>
        <blockquote>
        <p>[<i>Note:</i> These semantics distinguish between 
        <code>p</code> being known not to exist, 
        <code>p</code> existing but not being able to determine its attributes, 
        and there being an error that prevents even knowing if 
        <code>p</code> exists. These 
        distinctions are important to some use cases.&nbsp;<i>--end note</i>]</p>
    </blockquote>
    <p>Otherwise,</p>
    <ul>
      <li>
      <p>If the attributes indicate a regular file, as if by <i>POSIX</i>&nbsp;<a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">S_ISREG()</a>, 
      return <code>
      file_status(regular_file)</code>. [<i>Note:</i> <code>
regular_file</code> implies appropriate <code>&lt;fstream&gt;</code> operations 
      would succeed, assuming no hardware, permission, access, or race condition 
      errors. Lack of
<code>regular_file</code> does not necessarily imply <code>&lt;fstream&gt;</code> operations would 
fail on a directory.
<i>-- end note</i>]<br>
&nbsp;</li>
      <li>
      <p>Otherwise, if the attributes indicate a directory, as if by <i>POSIX</i>
      <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">S_ISDIR()</a>, 
      return <code>
      file_status(directory_file)</code>. [<i>Note:</i> <code>directory_file</code> implies <code>
directory_iterator(p)</code>would succeed.
<i>-- end note</i>]<br>
&nbsp;</li>
      <li>
      <p>Otherwise, if the attributes indicate a block special file, as if by <i>POSIX</i>
      <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">S_ISBLK()</a>, 
      return <code>
      file_status(block_file)</code>.<br>
&nbsp;</li>
      <li>
      <p>Otherwise, if the attributes indicate a character special file, as if by <i>POSIX</i>
      <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">S_ISCHR()</a>, 
      return <code>
      file_status(character_file)</code>.<br>
&nbsp;</li>
      <li>
      <p>Otherwise, if the attributes indicate a fifo or pipe file, as if by <i>POSIX</i>
      <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">S_ISFIFO()</a>, 
      return <code>
      file_status(fifo_file)</code>.<br>
&nbsp;</li>
      <li>
      <p>Otherwise, if the attributes indicate a socket, as if by <i>POSIX</i>
      <a href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">S_ISSOCK()</a>, 
      return <code>
      file_status(socket_file)</code>.<br>
&nbsp;</li>
      <li>
      <p>Otherwise, return <code>
      file_status(type_unknown)</code>.</li>
    </ul>
    </blockquote>
<p><i>Throws:</i> Nothing.</p>
      <p><i>Remarks:</i> If a symbolic link is encountered during pathname 
      resolution, 
      pathname resolution continues using the contents of the symbolic link.</p>
</blockquote>
  
<pre>bool <a name="status_known">status_known</a>(file_status s);</pre>
  
<blockquote>
  <p><i>Returns:</i>
  <code>s.type() != status_error</code></p>
  <p><i>Throws:</i> Nothing.</p>
</blockquote>
  
<pre>file_status <a name="symlink_status">symlink_status</a>(const path&amp; p);
file_status <a name="symlink_status2">symlink_status</a>(const path&amp; p, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Effects:</i>&nbsp; Same as <a href="#status">status()</a>, above, 
  except that the attributes 
    of
    <code>p</code> are determined as if by<i> POSIX </i> <code>
    <a href="http://www.opengroup.org/onlinepubs/000095399/functions/lstat.html">
    lstat()</a></code>.</p>
</blockquote>
<blockquote>
      <p><i>Returns:</i> Same as <a href="#status">status()</a>, above, except 
      that if the attributes indicate a symbolic link, as if by <i>POSIX</i>
      <a class="external" href="http://www.opengroup.org/onlinepubs/000095399/basedefs/sys/stat.h.html">
      S_ISLNK()</a>, return <code>file_status(symlink_file)</code>.</p>
<p><i>Throws:</i> Nothing.</p>
      <p><i>Remarks:</i> Pathname resolution terminates if <code>p</code> names a symbolic link.</p>
</blockquote>
  
<pre>path <a name="system_complete">system_complete</a>(const path&amp; p);
path <a name="system_complete2">system_complete</a>(const path&amp; p, error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Effects:</i> Composes an absolute path from <code>p</code>, using the 
  same rules used by the operating system to resolve a path passed as the 
  filename argument to standard library open functions.</p>
  <p><i>Returns:</i> The composed path.</p>
  <p><i>Postcondition:</i> For the returned path, <code>rp,</code> <code>
  rp.is_absolute()</code> is true.</p>
  <p>[<i>Note:</i> For <i>POSIX</i>, <code>system_complete(p)</code> has the same semantics as
  <code>complete(p, current_path())</code>.</p>
  <p><a name="windows_effects">For <i>Windows</i></a>, <code>system_complete(p)</code> has the 
  same semantics as <code>complete(ph, current_path())</code> if 
  <code>p.is_absolute() || !p.has_root_name()</code> or <code>p</code> and <code>base</code> have the same
  <code>root_name()</code>. 
  Otherwise it acts like <code>complete(p, kinky)</code>, where <code>kinky</code> 
  is the current directory for the <code>p.root_name()</code> drive. This will 
  be the current directory of that drive the last time it was set, and thus may 
  be <b>residue left over from a prior program</b> run by the command 
  processor! Although these semantics are often useful, they are also very 
  error-prone.</p>
  <p>See <a href="#complete_note">
  <i>complete()</i> note</a> for usage suggestions. <i>-- end note</i>]</p>
</blockquote>
  
<pre>path <a name="temp_directory_path">temp_directory_path</a>();
path temp_directory_path(error_code&amp; ec);</pre>
  
<blockquote>
  <p><i>Returns:</i> A directory path suitable for temporary files under the 
  conventions of the operating system. The specifics of how this path is 
  determined are implementation defined. An error shall be reported if<code> !exists(p) 
  || !is_directory(p)</code>, where <code>p</code> is the path to be returned.</p>
  <p><i>POSIX:</i> The path supplied by the first environment variable found in the 
  list TMPDIR, TMP, TEMP, TEMPDIR. If none of these are found, <code>&quot;/tmp&quot;</code>.</p>
  <p><i>Windows:</i> The path reported by the <i>Windows</i> <code>GetTempPath</code> API function.</p>
  <p><i>Throws:</i> As specified in <a href="#Error-reporting">
  Error reporting</a>.</p>
  <p>[<i>Note: </i>The <code>temp_directory_path()</code> name was chosen to emphasize that the return is a 
  path, not just a single directory name.&nbsp; <i>-- end note</i>]</p>
</blockquote>
  
<pre>path <a name="unique_path">unique_path</a>(const path&amp; model=&quot;%%%%-%%%%-%%%%-%%%%&quot;);
path unique_path(const path&amp; model, error_code&amp; ec);</pre>
  
<blockquote>
  <p>The <code>unique_path</code> function generates a path name suitable for 
  creating temporary files, including directories. The name is based 
  on a model that uses the percent sign character to specify replacement by a 
  random hexadecimal digit. [<i>Note:</i> The more bits of randomness in the 
  generated path name, the less likelihood of prior existence or being guessed. 
  Each replacement hexadecimal digit in the model adds four bits of randomness. 
  The default model thus provides 64 bits of randomness. This is sufficient for 
  most applications. <i>--end note</i>]</p>
  <p><i>Returns:</i> A path identical to <code>model</code>, except that each 
  occurrence of a percent sign character is replaced by a random hexadecimal 
  digit character in the range 0-9, a-f.</p>
  <p><i>Throws:</i> As specified in
  <a href="#Error-reporting">
  Error reporting</a>.</p>
  <p><i>Remarks:</i> Implementations are encouraged to obtain the required 
  randomness via a
  <a href="http://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator">
  cryptographically secure pseudo-random number generator</a>, such as one 
  provided by the operating system. [<i>Note</i>: Such generators may block 
  until sufficient entropy develops. <i>--end note</i>]</p>
</blockquote>
<h2>Additions to <a name="File-streams">Header</a> <code>&lt;fstream&gt;</code></h2>
<p>Replacements are provided for the file stream classes from the C++ standard 
library's <code>&lt;fstream&gt;</code> header. These replacement classes publicly 
inherit from the standard library classes. Constructors and open functions take <code>
const path&amp;</code> arguments. There are no other differences in syntax or 
semantics.</p>

<pre>namespace std { namespace tr2 {
  namespace filesystem
  {
    template &lt; class charT, class traits = char_traits&lt;charT&gt; &gt;
    class basic_filebuf : public std::basic_filebuf&lt;charT,traits&gt;
    {
    public:
      basic_filebuf&lt;charT,traits&gt;*
        open(const path&amp; p, std::ios_base::openmode mode);
    };

    template &lt; class charT, class traits = char_traits&lt;charT&gt; &gt;
    class basic_ifstream : public std::basic_ifstream&lt;charT,traits&gt;
    {
    public:
      explicit basic_ifstream(const path&amp; p, std::ios_base::openmode mode=ios_base::in)
      void open(const path&amp; p, std::ios_base::openmode mode=std::ios_base::in);
    };

    template &lt; class charT, class traits = char_traits&lt;charT&gt; &gt;
    class basic_ofstream : public std::basic_ofstream&lt;charT,traits&gt;
    {
    public:
      explicit basic_ofstream(const path&amp; p, std::ios_base::openmode mode=ios_base::out);
      void open(const path&amp; p, std::ios_base::openmode mode=std::ios_base::out);
    };

    template &lt; class charT, class traits = char_traits&lt;charT&gt; &gt;
    class basic_fstream : public std::basic_fstream&lt;charT,traits&gt;
    {
    public:
      explicit basic_fstream(const path&amp; p,
        std::ios_base::openmode mode=std::ios_base::in | std::ios_base::out);
      void open(const path&amp; p,
        std::ios_base::openmode mode=std::ios_base::in | std::ios_base::out);
    };

    typedef basic_filebuf&lt;char&gt; filebuf;
    typedef basic_ifstream&lt;char&gt; ifstream;
    typedef basic_ofstream&lt;char&gt; ofstream;
    typedef basic_fstream&lt;char&gt; fstream;

    typedef basic_filebuf&lt;wchar_t&gt; wfilebuf;
    typedef basic_ifstream&lt;wchar_t&gt; wifstream;
    typedef basic_fstream&lt;wchar_t&gt; wfstream;
    typedef basic_ofstream&lt;wchar_t&gt; wofstream;
    
  } // namespace filesystem
}} // namespaces std and tr2</pre>

<p><i>End of the proposed wording</i></p>

  <hr>

<h2><a name="Path-decomposition-table">Path decomposition table</a></h2>
<p>The table is generated by a program compiled with the Boost implementation.</p>
<p>Shaded entries indicate cases where <i>POSIX</i> and <i>Windows</i> 
implementations yield different results. The top value is the
<i>POSIX</i> result and the bottom value is the <i>Windows</i> result.
<p align="center"><b><font size="4">Path Decomposition Table</font></b><table border="1" cellspacing="0" cellpadding="5">
<p>
<tr><td>
  <p><b>Constructor<br>argument</b></td>
<td>
<p><b>Iteration<br>over<br>Elements</b></td>
<td>
<p><b><code>string()</code></b></td>
<td>
<p><b><code>generic_<br>string()</code></b></td>
<td>
<p><b><code>root_<br>path()</code></b></td>
<td>
<p><b><code>root_<br>name()</code></b></td>
<td>
<p><b><code>root_<br>directory()</code></b></td>
<td>
<p><b><code>relative_<br>path()</code></b></td>
<td>
<p><b><code>parent_<br>path()</code></b></td>
<td>
<p><b><code>filename()</code></b></td>
</tr>
<tr>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
</tr>
<tr>
<td>
<p><code>.</code></td>
<td>
<p><code>.</code></td>
<td>
<p><code>.</code></td>
<td>
<p><code>.</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>.</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>.</code></td>
</tr>
<tr>
<td>
<p><code>..</code></td>
<td>
<p><code>..</code></td>
<td>
<p><code>..</code></td>
<td>
<p><code>..</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>..</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>..</code></td>
</tr>
<tr>
<td>
<p><code>foo</code></td>
<td>
<p><code>foo</code></td>
<td>
<p><code>foo</code></td>
<td>
<p><code>foo</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>foo</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>foo</code></td>
</tr>
<tr>
<td>
<p><code>/</code></td>
<td>
<p><code>/</code></td>
<td>
<p><code>/</code></td>
<td>
<p><code>/</code></td>
<td>
<p><code>/</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>/</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>/</code></td>
</tr>
<tr>
<td>
<p><code>/foo</code></td>
<td>
<p><code>/,foo</code></td>
<td>
<p><code>/foo</code></td>
<td>
<p><code>/foo</code></td>
<td>
<p><code>/</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>/</code></td>
<td>
<p><code>foo</code></td>
<td>
<p><code>/</code></td>
<td>
<p><code>foo</code></td>
</tr>
<tr>
<td>
<p><code>foo/</code></td>
<td>
<p><code>foo,.</code></td>
<td>
<p><code>foo/</code></td>
<td>
<p><code>foo/</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>foo/</code></td>
<td>
<p><code>foo</code></td>
<td>
<p><code>.</code></td>
</tr>
<tr>
<td>
<p><code>/foo/</code></td>
<td>
<p><code>/,foo,.</code></td>
<td>
<p><code>/foo/</code></td>
<td>
<p><code>/foo/</code></td>
<td>
<p><code>/</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>/</code></td>
<td>
<p><code>foo/</code></td>
<td>
<p><code>/foo</code></td>
<td>
<p><code>.</code></td>
</tr>
<tr>
<td>
<p><code>foo/bar</code></td>
<td>
<p><code>foo,bar</code></td>
<td>
<p><code>foo/bar</code></td>
<td>
<p><code>foo/bar</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>foo/bar</code></td>
<td>
<p><code>foo</code></td>
<td>
<p><code>bar</code></td>
</tr>
<tr>
<td>
<p><code>/foo/bar</code></td>
<td>
<p><code>/,foo,bar</code></td>
<td>
<p><code>/foo/bar</code></td>
<td>
<p><code>/foo/bar</code></td>
<td>
<p><code>/</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>/</code></td>
<td>
<p><code>foo/bar</code></td>
<td>
<p><code>/foo</code></td>
<td>
<p><code>bar</code></td>
</tr>
<tr>
<td>
<p><code>//net</code></td>
<td>
<p><code>//net</code></td>
<td>
<p><code>//net</code></td>
<td>
<p><code>//net</code></td>
<td>
<p><code>//net</code></td>
<td>
<p><code>//net</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>//net</code></td>
</tr>
<tr>
<td>
<p><code>//net/foo</code></td>
<td>
<p><code>//net,/,foo</code></td>
<td>
<p><code>//net/foo</code></td>
<td>
<p><code>//net/foo</code></td>
<td>
<p><code>//net/</code></td>
<td>
<p><code>//net</code></td>
<td>
<p><code>/</code></td>
<td>
<p><code>foo</code></td>
<td>
<p><code>//net/</code></td>
<td>
<p><code>foo</code></td>
</tr>
<tr>
<td>
<p><code>///foo///</code></td>
<td>
<p><code>/,foo,.</code></td>
<td>
<p><code>///foo///</code></td>
<td>
<p><code>///foo///</code></td>
<td>
<p><code>/</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>/</code></td>
<td>
<p><code>foo///</code></td>
<td>
<p><code>///foo</code></td>
<td>
<p><code>.</code></td>
</tr>
<tr>
<td>
<p><code>///foo///bar</code></td>
<td>
<p><code>/,foo,bar</code></td>
<td>
<p><code>///foo///bar</code></td>
<td>
<p><code>///foo///bar</code></td>
<td>
<p><code>/</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>/</code></td>
<td>
<p><code>foo///bar</code></td>
<td>
<p><code>///foo</code></td>
<td>
<p><code>bar</code></td>
</tr>
<tr>
<td>
<p><code>/.</code></td>
<td>
<p><code>/,.</code></td>
<td>
<p><code>/.</code></td>
<td>
<p><code>/.</code></td>
<td>
<p><code>/</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>/</code></td>
<td>
<p><code>.</code></td>
<td>
<p><code>/</code></td>
<td>
<p><code>.</code></td>
</tr>
<tr>
<td>
<p><code>./</code></td>
<td>
<p><code>.,.</code></td>
<td>
<p><code>./</code></td>
<td>
<p><code>./</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>./</code></td>
<td>
<p><code>.</code></td>
<td>
<p><code>.</code></td>
</tr>
<tr>
<td>
<p><code>/..</code></td>
<td>
<p><code>/,..</code></td>
<td>
<p><code>/..</code></td>
<td>
<p><code>/..</code></td>
<td>
<p><code>/</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>/</code></td>
<td>
<p><code>..</code></td>
<td>
<p><code>/</code></td>
<td>
<p><code>..</code></td>
</tr>
<tr>
<td>
<p><code>../</code></td>
<td>
<p><code>..,.</code></td>
<td>
<p><code>../</code></td>
<td>
<p><code>../</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>../</code></td>
<td>
<p><code>..</code></td>
<td>
<p><code>.</code></td>
</tr>
<tr>
<td>
<p><code>foo/.</code></td>
<td>
<p><code>foo,.</code></td>
<td>
<p><code>foo/.</code></td>
<td>
<p><code>foo/.</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>foo/.</code></td>
<td>
<p><code>foo</code></td>
<td>
<p><code>.</code></td>
</tr>
<tr>
<td>
<p><code>foo/..</code></td>
<td>
<p><code>foo,..</code></td>
<td>
<p><code>foo/..</code></td>
<td>
<p><code>foo/..</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>foo/..</code></td>
<td>
<p><code>foo</code></td>
<td>
<p><code>..</code></td>
</tr>
<tr>
<td>
<p><code>foo/./</code></td>
<td>
<p><code>foo,.,.</code></td>
<td>
<p><code>foo/./</code></td>
<td>
<p><code>foo/./</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>foo/./</code></td>
<td>
<p><code>foo/.</code></td>
<td>
<p><code>.</code></td>
</tr>
<tr>
<td>
<p><code>foo/./bar</code></td>
<td>
<p><code>foo,.,bar</code></td>
<td>
<p><code>foo/./bar</code></td>
<td>
<p><code>foo/./bar</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>foo/./bar</code></td>
<td>
<p><code>foo/.</code></td>
<td>
<p><code>bar</code></td>
</tr>
<tr>
<td>
<p><code>foo/..</code></td>
<td>
<p><code>foo,..</code></td>
<td>
<p><code>foo/..</code></td>
<td>
<p><code>foo/..</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>foo/..</code></td>
<td>
<p><code>foo</code></td>
<td>
<p><code>..</code></td>
</tr>
<tr>
<td>
<p><code>foo/../</code></td>
<td>
<p><code>foo,..,.</code></td>
<td>
<p><code>foo/../</code></td>
<td>
<p><code>foo/../</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>foo/../</code></td>
<td>
<p><code>foo/..</code></td>
<td>
<p><code>.</code></td>
</tr>
<tr>
<td>
<p><code>foo/../bar</code></td>
<td>
<p><code>foo,..,bar</code></td>
<td>
<p><code>foo/../bar</code></td>
<td>
<p><code>foo/../bar</code></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>foo/../bar</code></td>
<td>
<p><code>foo/..</code></td>
<td>
<p><code>bar</code></td>
</tr>
<tr>
<td>
<p><code>c:</code></td>
<td>
<p><code>c:</code></td>
<td>
<p><code>c:</code></td>
<td>
<p><code>c:</code></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:</code><br><font size="-1"><i>empty</i></font></span></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>c:</code></td>
</tr>
<tr>
<td>
<p><code>c:/</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:,.</code><br><code>c:,/</code></span></td>
<td>
<p><code>c:/</code></td>
<td>
<p><code>c:/</code></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:/</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>/</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:/</code><br><font size="-1"><i>empty</i></font></span></td>
<td>
<p><code>c:</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>.</code><br><code>/</code></span></td>
</tr>
<tr>
<td>
<p><code>c:foo</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:foo</code><br><code>c:,foo</code></span></td>
<td>
<p><code>c:foo</code></td>
<td>
<p><code>c:foo</code></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:foo</code><br><code>foo</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:foo</code><br><code>foo</code></span></td>
</tr>
<tr>
<td>
<p><code>c:/foo</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:,foo</code><br><code>c:,/,foo</code></span></td>
<td>
<p><code>c:/foo</code></td>
<td>
<p><code>c:/foo</code></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:/</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>/</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:/foo</code><br><code>foo</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:</code><br><code>c:/</code></span></td>
<td>
<p><code>foo</code></td>
</tr>
<tr>
<td>
<p><code>c:foo/</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:foo,.</code><br><code>c:,foo,.</code></span></td>
<td>
<p><code>c:foo/</code></td>
<td>
<p><code>c:foo/</code></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:foo/</code><br><code>foo/</code></span></td>
<td>
<p><code>c:foo</code></td>
<td>
<p><code>.</code></td>
</tr>
<tr>
<td>
<p><code>c:/foo/</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:,foo,.</code><br><code>c:,/,foo,.</code></span></td>
<td>
<p><code>c:/foo/</code></td>
<td>
<p><code>c:/foo/</code></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:/</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>/</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:/foo/</code><br><code>foo/</code></span></td>
<td>
<p><code>c:/foo</code></td>
<td>
<p><code>.</code></td>
</tr>
<tr>
<td>
<p><code>c:/foo/bar</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:,foo,bar</code><br><code>c:,/,foo,bar</code></span></td>
<td>
<p><code>c:/foo/bar</code></td>
<td>
<p><code>c:/foo/bar</code></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:/</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>/</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:/foo/bar</code><br><code>foo/bar</code></span></td>
<td>
<p><code>c:/foo</code></td>
<td>
<p><code>bar</code></td>
</tr>
<tr>
<td>
<p><code>prn:</code></td>
<td>
<p><code>prn:</code></td>
<td>
<p><code>prn:</code></td>
<td>
<p><code>prn:</code></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>prn:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>prn:</code></span></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><span style="background-color: #CCFFCC"><code>prn:</code><br><font size="-1"><i>empty</i></font></span></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><code>prn:</code></td>
</tr>
<tr>
<td>
<p><code>c:\</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\</code><br><code>c:,/</code></span></td>
<td>
<p><code>c:\</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\</code><br><code>c:/</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:\</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>\</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\</code><br><font size="-1"><i>empty</i></font></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\</code><br><code>\</code></span></td>
</tr>
<tr>
<td>
<p><code>c:foo</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:foo</code><br><code>c:,foo</code></span></td>
<td>
<p><code>c:foo</code></td>
<td>
<p><code>c:foo</code></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:foo</code><br><code>foo</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:foo</code><br><code>foo</code></span></td>
</tr>
<tr>
<td>
<p><code>c:\foo</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\foo</code><br><code>c:,/,foo</code></span></td>
<td>
<p><code>c:\foo</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\foo</code><br><code>c:/foo</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:\</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>\</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\foo</code><br><code>foo</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:\</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\foo</code><br><code>foo</code></span></td>
</tr>
<tr>
<td>
<p><code>c:foo\</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:foo\</code><br><code>c:,foo,.</code></span></td>
<td>
<p><code>c:foo\</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:foo\</code><br><code>c:foo/</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><font size="-1"><i>empty</i></font></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:foo\</code><br><code>foo\</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:foo</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:foo\</code><br><code>.</code></span></td>
</tr>
<tr>
<td>
<p><code>c:\foo\</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\foo\</code><br><code>c:,/,foo,.</code></span></td>
<td>
<p><code>c:\foo\</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\foo\</code><br><code>c:/foo/</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:\</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>\</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\foo\</code><br><code>foo\</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:\foo</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\foo\</code><br><code>.</code></span></td>
</tr>
<tr>
<td>
<p><code>c:\foo/</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\foo,.</code><br><code>c:,/,foo,.</code></span></td>
<td>
<p><code>c:\foo/</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\foo/</code><br><code>c:/foo/</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:\</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>\</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:\foo/</code><br><code>foo/</code></span></td>
<td>
<p><code>c:\foo</code></td>
<td>
<p><code>.</code></td>
</tr>
<tr>
<td>
<p><code>c:/foo\bar</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:,foo\bar</code><br><code>c:,/,foo,bar</code></span></td>
<td>
<p><code>c:/foo\bar</code></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:/foo\bar</code><br><code>c:/foo/bar</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:/</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>c:</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><font size="-1"><i>empty</i></font><br><code>/</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:/foo\bar</code><br><code>foo\bar</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>c:</code><br><code>c:/foo</code></span></td>
<td>
<p><span style="background-color: #CCFFCC"><code>foo\bar</code><br><code>bar</code></span></td>
</tr>
</table>
<h2><a name="Acknowledgements">Acknowledgements</a></h2>
<p>This Filesystem Library is dedicated to my wife, Sonda, who provided the 
support necessary to see both a trial implementation and the proposal itself 
through to completion. She gave me the strength to continue after a difficult 
year of cancer treatment in the middle of it all.</p>
<p>Many people contributed technical comments, ideas, and suggestions to the 
Boost Filesystem Library.</p>
<p>Dietmar Kuehl contributed the original Boost Filesystem Library directory_iterator design. Peter Dimov, Walter Landry, Rob Stewart, and Thomas 
Witt were particularly helpful in refining the library.</p>
<p>The create_directories, extension, basename, and replace_extension functions 
were developed by Vladimir Prus. The temp_directory_path function was 
contributed by Jeff Flinn.</p>
<p>Howard Hinnant and John Maddock reviewed a draft of the version 2 proposal, and 
identified a number of mistakes or weaknesses, resulting in a more polished 
final document.</p>
<p>Peter Dimov suggested a single class path, with member templates to adapt to 
multiple string types. His idea became the basis for the version 3 path design.</p>
<hr>
  
</body>

</html>