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

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  <refentry id="function.array-merge">
   <refnamediv>
    <refname>array_merge</refname>
    <refpurpose>Merge one or more arrays</refpurpose>
   </refnamediv>
   <refsect1>
    <title>Description</title>
     <methodsynopsis>
      <type>array</type><methodname>array_merge</methodname>
      <methodparam><type>array</type><parameter>array1</parameter></methodparam>
      <methodparam choice="opt"><type>array</type><parameter>array2</parameter></methodparam>
      <methodparam choice="opt"><type>array</type><parameter>...</parameter></methodparam>
     </methodsynopsis>
    <para>
     <function>array_merge</function> merges the elements of one or
     more arrays together so that the values of one are appended to
     the end of the previous one.  It returns the resulting array.
    </para>
    <para>
     If the input arrays have the same string keys, then the later value for
     that key will overwrite the previous one.  If, however, the arrays
     contain numeric keys, the later value will <emphasis
     role="strong">not</emphasis> overwrite the original value, but will be
     appended.
    </para>
    <para>
     If only one array is given and the array is numerically indexed, the
     keys get reindexed in a continuous way. For associative arrays, duplicate
     entries will be merged into the last one. See example three for details.
    </para>
    <para>
     <example>
      <title><function>array_merge</function> example</title>
      <programlisting role="php">
<![CDATA[
<?php
$array1 = array("color" => "red", 2, 4);
$array2 = array("a", "b", "color" => "green", "shape" => "trapezoid", 4);
$result = array_merge($array1, $array2);
print_r($result);
?>
]]>
      </programlisting>
      <para>
       The <varname>$result</varname> is:
      </para>
      <screen role="php">
<![CDATA[
Array
(
    [color] => green
    [0] => 2
    [1] => 4
    [2] => a
    [3] => b
    [shape] => trapezoid
    [4] => 4
)
]]>
      </screen>
     </example>
    </para>
    <para>
     <example>
      <title>Simple <function>array_merge</function> example</title>
      <programlisting role="php">
<![CDATA[
<?php
$array1 = array();
$array2 = array(1 => "data");
$result = array_merge($array1, $array2);
?>
]]>
      </programlisting>
      <para>
       Don't forget that numeric keys will be renumbered!
      </para>
      <screen role="php">
<![CDATA[
Array
(
    [0] => data
)
]]>
      </screen>
      <para>
       If you want to completely preserve the arrays and just want to append
       them to each other, use the <literal>+</literal> operator:
      </para>
      <programlisting role="php">
<![CDATA[
<?php
$array1 = array();
$array2 = array(1 => "data");
$result = $array1 + $array2;
?>
]]>
      </programlisting>
      <para>
       The numeric key will be preserved and thus the association remains.
      </para>
      <screen role="php">
<![CDATA[
Array
(
    [1] => data
)
]]>
      </screen>
     </example>
     <example>
      <title><function>array_merge</function> example</title>
      <programlisting role="php">
<![CDATA[
<?php
$array_one = array(0 => "jay", 1 => "bob", 2 => "randal", 3 => "dante");
$array_two = array("jay" => "bob", "randal" => "dante", "jay" => "jason");

unset($array_one[2]);

$result_one = array_merge($array_one);
$result_two = array_merge($array_two);

print_r($result_one);
print_r($result_two);
?>
]]>
      </programlisting>
      <para>
       The output is: 
      </para>
      <screen role="php">
<![CDATA[
Array
(
    [0] => jay
    [1] => bob
    [2] => dante
)
Array
(
    [jay] => jason
    [randal] => dante
)
]]>
      </screen>
     </example>
    </para>
    <note>
     <para>
      Shared keys will be overwritten on a first-come first-served basis.
     </para>
    </note>
    <para>
     See also <function>array_merge_recursive</function>,
     <function>array_combine</function> and
     <link linkend="language.operators.array">array operators</link>.
    </para>
   </refsect1>
  </refentry>

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