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

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<!-- $Revision: 1.11 $ -->
<!-- splitted from ./en/functions/array.xml, last change in rev 1.56 -->
  <refentry id="function.in-array">
   <refnamediv>
    <refname>in_array</refname>
    <refpurpose>Checks if a value exists in an array</refpurpose>
   </refnamediv>
   <refsect1>
    <title>Description</title>
     <methodsynopsis>
      <type>bool</type><methodname>in_array</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></methodparam>
     </methodsynopsis>
    <para>
     Searches <parameter>haystack</parameter> for
     <parameter>needle</parameter> and returns &true;
     if it is found in the array, &false; otherwise.
    </para>
    <para>
     If the third parameter <parameter>strict</parameter> is set to
     &true; then the <function>in_array</function> function
     will also check the <link linkend="language.types">types</link> of
     the <parameter>needle</parameter> in the <parameter>haystack</parameter>.
    </para>
    <note>
     <para>
      If <parameter>needle</parameter> is a string, the comparison is done in
      a case-sensitive manner.
     </para>
    </note>
    <note>
     <para>
      In PHP versions before 4.2.0 <parameter>needle</parameter> was not
      allowed to be an array.
     </para>
    </note>
    <para>
     <example>
      <title><function>in_array</function> example</title>
      <programlisting role="php">
<![CDATA[
<?php
$os = array("Mac", "NT", "Irix", "Linux");
if (in_array("Irix", $os)) {
    echo "Got Irix";
}
if (in_array("mac", $os)) {
    echo "Got mac";
}
?>
]]>
      </programlisting>
      <para>
       The second condition fails because <function>in_array</function>
       is case-sensitive, so the program above will display:
      </para>
      <screen>
<![CDATA[
Got Irix
]]>
      </screen>
     </example>
    </para>
    <para>
     <example>
      <title><function>in_array</function> with strict example</title>
      <programlisting role="php">
<![CDATA[
<?php
$a = array('1.10', 12.4, 1.13);

if (in_array('12.4', $a, true)) {
    echo "'12.4' found with strict check\n";
}

if (in_array(1.13, $a, true)) {
    echo "1.13 found with strict check\n";
}
?>
]]>
      </programlisting>
      <para>
       This will display:
      </para>
      <screen>
<![CDATA[
1.13 found with strict check
]]>
      </screen>
     </example>
    </para>
    <para>
     <example>
      <title><function>in_array</function> with an array as needle</title>
      <programlisting role="php">
<![CDATA[
<?php
$a = array(array('p', 'h'), array('p', 'r'), 'o');

if (in_array(array('p', 'h'), $a)) {
    echo "'ph' was found\n";
}

if (in_array(array('f', 'i'), $a)) {
    echo "'fi' was found\n";
}

if (in_array('o', $a)) {
    echo "'o' was found\n";
}
?>
]]>
      </programlisting>
      <para>
       Outputs:
      </para>
      <screen>
<![CDATA[
  'ph' was found
  'o' was found
]]>
      </screen>
     </example>
    </para>
    <para>
     See also <function>array_search</function>,
     <function>array_key_exists</function>, and
     <function>isset</function>.
    </para>
   </refsect1>
  </refentry>

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