Array Functions
PHP Manual


(PHP 5, PHP 7)

array_diff_uassocComputes the difference of arrays with additional index check which is performed by a user supplied callback function


array array_diff_uassoc ( array $array1 , array $array2 [, array $... ], callable $key_compare_func )

Compares array1 against array2 and returns the difference. Unlike array_diff() the array keys are used in the comparison.

Unlike array_diff_assoc() a user supplied callback function is used for the indices comparison, not internal function.



The array to compare from


An array to compare against


More arrays to compare against


The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second. Note that before PHP 7.0.0 this integer had to be in the range from -2147483648 to 2147483647.

int callback ( mixed $a, mixed $b )

Return Values

Returns an array containing all the entries from array1 that are not present in any of the other arrays.


Example #1 array_diff_uassoc() example

The "a" => "green" pair is present in both arrays and thus it is not in the output from the function. Unlike this, the pair 0 => "red" is in the output because in the second argument "red" has key which is 1.

function key_compare_func($a$b)
    if (
$a === $b) {
    return (
$a $b)? 1:-1;

$array1 = array("a" => "green""b" => "brown""c" => "blue""red");
$array2 = array("a" => "green""yellow""red");
$result array_diff_uassoc($array1$array2"key_compare_func");

The above example will output:

    [b] => brown
    [c] => blue
    [0] => red

The equality of 2 indices is checked by the user supplied callback function.



This function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using, for example, array_diff_uassoc($array1[0], $array2[0], "key_compare_func");.

See Also

Array Functions
PHP Manual