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array_merge_recursive

(PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8)

array_merge_recursiveMerge one or more arrays recursively

Description

array_merge_recursive(array ...$arrays): array

array_merge_recursive() 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.

If the input arrays have the same string keys, then the values for these keys are merged together into an array, and this is done recursively, so that if one of the values is an array itself, the function will merge it with a corresponding entry in another array too. If, however, the arrays have the same numeric key, the later value will not overwrite the original value, but will be appended.

Parameters

arrays

Variable list of arrays to recursively merge.

Return Values

An array of values resulted from merging the arguments together. If called without any arguments, returns an empty array.

Changelog

Version Description
7.4.0 This function can now be called without any parameter. Formerly, at least one parameter has been required.

Examples

Example #1 array_merge_recursive() example

<?php
$ar1
= array("color" => array("favorite" => "red"), 5);
$ar2 = array(10, "color" => array("favorite" => "green", "blue"));
$result = array_merge_recursive($ar1, $ar2);
print_r($result);
?>

The above example will output:

Array
(
    [color] => Array
        (
            [favorite] => Array
                (
                    [0] => red
                    [1] => green
                )

            [0] => blue
        )

    [0] => 5
    [1] => 10
)

See Also

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User Contributed Notes 1 note

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175
gabriel dot sobrinho at gmail dot com
15 years ago
I refactored the Daniel's function and I got it:

<?php
/**
* array_merge_recursive does indeed merge arrays, but it converts values with duplicate
* keys to arrays rather than overwriting the value in the first array with the duplicate
* value in the second array, as array_merge does. I.e., with array_merge_recursive,
* this happens (documented behavior):
*
* array_merge_recursive(array('key' => 'org value'), array('key' => 'new value'));
* => array('key' => array('org value', 'new value'));
*
* array_merge_recursive_distinct does not change the datatypes of the values in the arrays.
* Matching keys' values in the second array overwrite those in the first array, as is the
* case with array_merge, i.e.:
*
* array_merge_recursive_distinct(array('key' => 'org value'), array('key' => 'new value'));
* => array('key' => array('new value'));
*
* Parameters are passed by reference, though only for performance reasons. They're not
* altered by this function.
*
* @param array $array1
* @param array $array2
* @return array
* @author Daniel <daniel (at) danielsmedegaardbuus (dot) dk>
* @author Gabriel Sobrinho <gabriel (dot) sobrinho (at) gmail (dot) com>
*/
function array_merge_recursive_distinct ( array &$array1, array &$array2 )
{
$merged = $array1;

foreach (
$array2 as $key => &$value )
{
if (
is_array ( $value ) && isset ( $merged [$key] ) && is_array ( $merged [$key] ) )
{
$merged [$key] = array_merge_recursive_distinct ( $merged [$key], $value );
}
else
{
$merged [$key] = $value;
}
}

return
$merged;
}
?>

This fix the E_NOTICE when the the first array doesn't have the key and the second array have a value which is a array.
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