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

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<refentry xml:id="function.array-unique" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>array_unique</refname>
  <refpurpose>Removes duplicate values from an array</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>array</type><methodname>array_unique</methodname>
   <methodparam><type>array</type><parameter>array</parameter></methodparam>
  </methodsynopsis>
  <para>
   Takes an input <parameter>array</parameter> and returns a new array
   without duplicate values.
  </para>
  <para>
   Note that keys are preserved. <function>array_unique</function> sorts
   the values treated as string at first, then will keep the first key
   encountered for every value, and ignore all following keys. It does not
   mean that the key of the first related value from the unsorted
   <parameter>array</parameter> will be kept.
  </para>
  <note>
   <simpara>
    Two elements are considered equal if and only if
    <literal>(string) $elem1 === (string) $elem2</literal>. In words:
    when the string representation is the same.
   </simpara>
   <simpara>
    The first element will be used.
   </simpara>
  </note>
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>array</parameter></term>
     <listitem>
      <para>
       The input array.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns the filtered array.
  </para>
 </refsect1>
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>array_unique</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
$input = array("a" => "green", "red", "b" => "green", "blue", "red");
$result = array_unique($input);
print_r($result);
?>
]]>
    </programlisting>
    &example.outputs;
    <screen role="php">
<![CDATA[
Array
(
    [a] => green
    [0] => red
    [1] => blue
)
]]>
    </screen>
   </example>
  </para>
  <para>
   <example>
    <title><function>array_unique</function> and types</title>
    <programlisting role="php">
<![CDATA[
<?php
$input = array(4, "4", "3", 4, 3, "3");
$result = array_unique($input);
var_dump($result);
?>
]]>
    </programlisting>
    &example.outputs;
    <screen role="php">
<![CDATA[
array(2) {
  [0] => int(4)
  [2] => string(1) "3"
}
]]>
    </screen>
   </example>
  </para>
 </refsect1>
</refentry>

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