The "array_udiff_assoc()" function computes the difference of arrays with additional index check, compares data by a callback function.

  array_udiff_assoc(array1,array2,array3...,function)

In the above syntax "array1" and "array2" are compared automatically for keys, then in the user defined function checks for the values, then returns an array of differing elements.

    <?php
    function funct1($x1,$x2) 
      {
      if ($x1===$x2)
	 {
	  return 0;
	  }
       return 1;
      }
    $a1=array("a"=>"Cat","b"=>"Dog","c"=>"Horse");
    $a2=array("a"=>"Cat","b"=>"Horse","c"=>"Dog");
    print_r(array_udiff_assoc($a1,$a2,"funct1"));
    ?>

    Array ( [b] Dog [c] => Horse )

In the above example the two arrays "a1", "a2" are compared for keys then for values to display the different elements.