archived-doc-en/reference/array/functions/array-unshift.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="function.array-unshift" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>array_unshift</refname>
  <refpurpose>Prepend one or more elements to the beginning of an array</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>int</type><methodname>array_unshift</methodname>
   <methodparam><type>array</type><parameter role="reference">array</parameter></methodparam>
   <methodparam rep="repeat"><type>mixed</type><parameter>values</parameter></methodparam>
  </methodsynopsis>
  <para>
   <function>array_unshift</function> prepends passed elements to the front
   of the <parameter>array</parameter>. Note that the list of elements is
   prepended as a whole, so that the prepended elements stay in the same
   order.  All numerical array keys will be modified to start counting from
   zero while literal keys won't be changed.
  </para>
  &note.reset-index;
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>array</parameter></term>
     <listitem>
      <para>
       The input array.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>values</parameter></term>
     <listitem>
      <para>
       The values to prepend.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns the new number of elements in the <parameter>array</parameter>.
  </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>7.3.0</entry>
       <entry>
        This function can now be called with only one parameter. Formerly, at
        least two parameters have been required.
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>array_unshift</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php

$queue = [
    "orange",
    "banana"
];

array_unshift($queue, "apple", "raspberry");

var_dump($queue);

?>
]]>
    </programlisting>
    &example.outputs;
    <screen role="php">
<![CDATA[
array(4) {
  [0] =>
  string(5) "apple"
  [1] =>
  string(9) "raspberry"
  [2] =>
  string(6) "orange"
  [3] =>
  string(6) "banana"
}
]]>
    </screen>
   </example>
  </para>
  <para>
   <example>
    <title>Usage with associative arrays</title>
    <para>
     If one associative array is prepended to another associative array,
     the prepended array is numerically indexed into the former array.
    </para>
    <programlisting role="php">
<![CDATA[
<?php

$foods = [
    'apples' => [
        'McIntosh' => 'red',
        'Granny Smith' => 'green',
    ],
    'oranges' => [
        'Navel' => 'orange',
        'Valencia' => 'orange',
    ],
];

$vegetables = [
    'lettuce' => [
        'Iceberg' => 'green',
        'Butterhead' => 'green',
    ],
    'carrots' => [
        'Deep Purple Hybrid' => 'purple',
        'Imperator' => 'orange',
    ],
    'cucumber' => [
        'Kirby' => 'green',
        'Gherkin' => 'green',
    ],
];

array_unshift($foods, $vegetables);

var_dump($foods);

?>
]]>
    </programlisting>
    &example.outputs;
    <screen role="php">
<![CDATA[
array(3) {
  [0]=>
  array(3) {
    ["lettuce"]=>
    array(2) {
      ["Iceberg"]=>
      string(5) "green"
      ["Butterhead"]=>
      string(5) "green"
    }
    ["carrots"]=>
    array(2) {
      ["Deep Purple Hybrid"]=>
      string(6) "purple"
      ["Imperator"]=>
      string(6) "orange"
    }
    ["cucumber"]=>
    array(2) {
      ["Kirby"]=>
      string(5) "green"
      ["Gherkin"]=>
      string(5) "green"
    }
  }
  ["apples"]=>
  array(2) {
    ["McIntosh"]=>
    string(3) "red"
    ["Granny Smith"]=>
    string(5) "green"
  }
  ["oranges"]=>
  array(2) {
    ["Navel"]=>
    string(6) "orange"
    ["Valencia"]=>
    string(6) "orange"
  }
}
]]>
    </screen>
   </example>
  </para>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>array_merge</function></member>
    <member><function>array_shift</function></member>
    <member><function>array_push</function></member>
    <member><function>array_pop</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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