array_diff_uassoc($a,$b,"key_compare_func")

<?php
function key_compare_func($a,$b){
  if($a === $b){
      return 0;
  }
  return($a>$b)?1:-1;
}
$a = array('a'=>'green','b'=>'brown','c'=>'blue','red');
$b = array('a'=>'green','yellow','red');
print_r(array_diff_uassoc($a,$b,"key_compare_func"));
输出：
Array
(
  [b] => brown
  [c] => blue
  [0] => red
)