php-doc-en/reference/array/functions/array-search.xml

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<refentry xml:id="function.array-search" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>array_search</refname>
  <refpurpose>Searches the array for a given value and returns the first corresponding key if successful</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>mixed</type><methodname>array_search</methodname>
   <methodparam><type>mixed</type><parameter>needle</parameter></methodparam>
   <methodparam><type>array</type><parameter>haystack</parameter></methodparam>
   <methodparam choice="opt"><type>bool</type><parameter>strict</parameter><initializer>false</initializer></methodparam>
  </methodsynopsis>
  <para>
   Searches <parameter>haystack</parameter> for <parameter>needle</parameter>.
  </para>
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>needle</parameter></term>
     <listitem>
      <para>
       The searched value.
      </para>
      <note>
       <para>
        If <parameter>needle</parameter> is a string, the comparison is done
        in a case-sensitive manner.
       </para>
      </note>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>haystack</parameter></term>
     <listitem>
      <para>
       The array.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>strict</parameter></term>
     <listitem>
      <para>
       If the third parameter <parameter>strict</parameter> is set to &true;
       then the <function>array_search</function> function will search for
       <emphasis>identical</emphasis> elements in the
       <parameter>haystack</parameter>. This means it will also perform a
       <link linkend="language.types">strict type comparison</link> of the
       <parameter>needle</parameter> in the <parameter>haystack</parameter>,
       and objects must be the same instance.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns the key for <parameter>needle</parameter> if it is found in the
   array, &false; otherwise.
  </para>
  <para>
   If <parameter>needle</parameter> is found in <parameter>haystack</parameter>
   more than once, the first matching key is returned. To return the keys for
   all matching values, use <function>array_keys</function> with the optional
   <parameter>search_value</parameter> parameter instead.
  </para>
  &return.falseproblem;
 </refsect1>
 <refsect1 role="changelog">
  &reftitle.changelog;
  <para>
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>&Version;</entry>
       <entry>&Description;</entry>
      </row>
     </thead>
     <tbody>
      <row>
       <entry>5.3.0</entry>
       <entry>
        As with all internal PHP functions as of 5.3.0,
        <function>array_search</function> returns &null; if invalid parameters
        are passed to it.
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>array_search</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
$array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red');

$key = array_search('green', $array); // $key = 2;
$key = array_search('red', $array);   // $key = 1;
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>array_keys</function></member>
    <member><function>array_values</function></member>
    <member><function>array_key_exists</function></member>
    <member><function>in_array</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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