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<refentry xml:id="function.preg-grep" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>preg_grep</refname>
  <refpurpose>Return array entries that match the pattern</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>array</type><methodname>preg_grep</methodname>
   <methodparam><type>string</type><parameter>pattern</parameter></methodparam>
   <methodparam><type>array</type><parameter>input</parameter></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>flags</parameter><initializer>0</initializer></methodparam>
  </methodsynopsis>
  <para>
   Returns the array consisting of the elements of the 
   <parameter>input</parameter> array that match the given
   <parameter>pattern</parameter>.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>pattern</parameter></term>
     <listitem>
      <para>
       The pattern to search for, as a string.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>input</parameter></term>
     <listitem>
      <para>
       The input array.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>flags</parameter></term>
     <listitem>
      <para>
       If set to <constant>PREG_GREP_INVERT</constant>, this function returns
       the elements of the input array that do <emphasis>not</emphasis> match
       the given <parameter>pattern</parameter>.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns an array indexed using the keys from the
   <parameter>input</parameter> array. 
  </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>4.2.0</entry>
       <entry>
        The <parameter>flags</parameter> parameter was added.
       </entry>
      </row>
      <row>
       <entry>4.0.4</entry>
       <entry>
        <para>
         Prior to this version, the returned array was indexed regardless of
         the keys of the <parameter>input</parameter> array.
        </para>
        <para>
         If you want to reproduce this old behavior, use 
         <function>array_values</function> on the returned array to reindex
          the values.
        </para>
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>
 
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>preg_grep</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
// return all array elements
// containing floating point numbers
$fl_array = preg_grep("/^(\d+)?\.\d+$/", $array);
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>

</refentry>

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