array_diff_assoc Computes the difference of arrays with additional index check arrayarray_diff_assoc arrayarray1 arrayarray2 array ... array_diff_assoc returns an array containing all the values from array1 that are not present in any of the other arguments. Note that the keys are used in the comparison unlike array_diff. "green", "b" => "brown", "c" => "blue", "red"); $array2 = array ("a" => "green", "yellow", "red"); $result = array_diff_assoc ($array1, $array2); /* The result is: Array ( [b] => brown [c] => blue [0] => red ) */ ?> ]]> In our example above you see the "a" => "green" pair is present in both arrays and thus it is not in the ouput from the function. Unlike this, the pair 0 => "red" is in the ouput because in the second argument "red" has key which is 1. Two values from key => value pairs are considered equal only if (string) $elem1 === (string) $elem2 . In other words a strict check takes place so the string representations must be the same. Please note that this function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using, for example, array_diff_assoc($array1[0], $array2[0]);. See also array_diff, array_intersect, and array_intersect_assoc.