array_diff_key

 array array_diff_key ( array $array1 , array $array2 [, array $... ] ) 

説明

Compares the keys from array1 against the keys from array2 and returns the difference. This function is like array_diff() except the comparison is done on the keys instead of the values.

戻り値

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