dirname.xml

<?xml version="1.0" encoding="utf-8"?>
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<refentry xmlns="http://docbook.org/ns/docbook" xml:id="function.dirname">
 <refnamediv>
  <refname>dirname</refname>
  <refpurpose>Returns a parent directory's path</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>string</type><methodname>dirname</methodname>
   <methodparam><type>string</type><parameter>path</parameter></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>levels</parameter><initializer>1</initializer></methodparam>
  </methodsynopsis>
  <para>
   Given a string containing the path of a file or directory, this function
   will return the parent directory's path that is
   <parameter>levels</parameter> up from the current directory.
  </para>
  <note>
   <para>
    <function>dirname</function> operates naively on the input string,
    and is not aware of the actual filesystem, or path components such
    as "<literal>..</literal>".
   </para>
  </note>
  <caution>
   <para>
    On Windows, <function>dirname</function> assumes the currently set codepage, so for it to see the
    correct directory name with multibyte character paths, the matching codepage must
    be set.
    If <parameter>path</parameter> contains characters which are invalid for the
    current codepage, the behavior of <function>dirname</function> is undefined.
   </para>
   <para>
    On other systems, <function>dirname</function> assumes <parameter>path</parameter>
    to be encoded in an ASCII compatible encoding. Otherwise, the behavior of
    the function is undefined.
   </para>
  </caution>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>path</parameter></term>
     <listitem>
      <para>
       A path.
      </para>
      <para>
       On Windows, both slash (<literal>/</literal>) and backslash
       (<literal>\</literal>) are used as directory separator character. In
       other environments, it is the forward slash (<literal>/</literal>).
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>levels</parameter></term>
     <listitem>
      <para>
       The number of parent directories to go up.
      </para>
      <para>
       This must be an integer greater than 0.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns the path of a parent directory. If there are no slashes in
   <parameter>path</parameter>, a dot ('<literal>.</literal>') is returned,
   indicating the current directory. Otherwise, the returned string is
   <parameter>path</parameter> with any trailing
   <literal>/component</literal> removed.
  </para>

  <caution>
   <para>
    Be careful when using this function in a loop that can reach the
    top-level directory as this can result in an infinite loop.
    <informalexample>
     <programlisting role="php">
<![CDATA[
<?php
dirname('.');    // Will return '.'.
dirname('/');    // Will return `\` on Windows and '/' on *nix systems.
dirname('\\');   // Will return `\` on Windows and '.' on *nix systems.
dirname('C:\\'); // Will return 'C:\' on Windows and '.' on *nix systems.
?>
]]>
     </programlisting>
    </informalexample>
   </para>
  </caution>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>dirname</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
echo dirname("/etc/passwd") . PHP_EOL;
echo dirname("/etc/") . PHP_EOL;
echo dirname(".") . PHP_EOL;
echo dirname("C:\\") . PHP_EOL;
echo dirname("/usr/local/lib", 2);
]]>
    </programlisting>
    &example.outputs.similar;
    <screen>
<![CDATA[
/etc
/ (or \ on Windows)
.
C:\
/usr
]]>
    </screen>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>basename</function></member>
    <member><function>pathinfo</function></member>
    <member><function>realpath</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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