php-doc-en/reference/strings/functions/strrpos.xml

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<refentry xmlns="http://docbook.org/ns/docbook" xml:id="function.strrpos">
 <refnamediv>
  <refname>strrpos</refname>
  <refpurpose>Find position of last occurrence of a char in a string</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>int</type><methodname>strrpos</methodname>
   <methodparam><type>string</type><parameter>haystack</parameter></methodparam>
   <methodparam><type>string</type><parameter>needle</parameter></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>offset</parameter><initializer>0</initializer></methodparam>
  </methodsynopsis>
  <para>
   Returns the numeric position of the last occurrence of
   <parameter>needle</parameter> in the
   <parameter>haystack</parameter> string.  Note that the needle in
   this case can only be a single character in PHP 4.  If a string is passed
   as the needle, then only the first character of that string will
   be used.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>haystack</parameter></term>
     <listitem>
      <para>
       The string to search in.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>needle</parameter></term>
     <listitem>
      <para>
       If <parameter>needle</parameter> is not a string, it is converted
       to an integer and applied as the ordinal value of a character.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>offset</parameter></term>
     <listitem>
      <para>
       May be specified to begin searching an arbitrary number of characters into
       the string.  Negative values will stop searching at an arbitrary point
       prior to the end of the string.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns the position where the needle exists. Returns &false; if the needle
   was not found.
  </para>
 </refsect1>
 
 <refsect1 role="changelog">
  &reftitle.changelog;
  <para>
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>&Version;</entry>
       <entry>&Description;</entry>
      </row>
     </thead>
     <tbody>
      <row>
       <entry>5.0.0</entry>
       <entry>
        The <parameter>needle</parameter> may now be a string of more than one
        character.
       </entry>
      </row>
      <row>
       <entry>5.0.0</entry>
       <entry>
        The <parameter>offset</parameter> parameter was introduced.
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>
 
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title>Checking if a needle is in the haystack</title>
    <para>
     It is easy to mistake the return values for "character found at
     position 0" and "character not found".  Here's how to detect
     the difference:
    </para>
    <programlisting role="php">
<![CDATA[
<?php

$pos = strrpos($mystring, "b");
if ($pos === false) { // note: three equal signs
    // not found...
}

?>
]]>
    </programlisting>
   </example>
  </para>
  <para>
   <example>
    <title>Searching with offsets</title>
    <programlisting role="php">
<![CDATA[
<?php
$foo = "0123456789a123456789b123456789c";

var_dump(strrpos($foo, '7', -5));  // Starts looking backwards five positions
                                   // from the end. Result: int(17)

var_dump(strrpos($foo, '7', 20));  // Starts searching 20 positions into the
                                   // string. Result: int(27)

var_dump(strrpos($foo, '7', 28));  // Result: bool(false)
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>strpos</function></member>
    <member><function>strripos</function></member>
    <member><function>strrchr</function></member>
    <member><function>substr</function></member>
    <member><function>stristr</function></member>
    <member><function>strstr</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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