The "array_intersect_uassoc()" function is used to compute the intersection of arrays with additional index check, compares indexes by a callback function.

The difference between array_intersect_uassoc() and array_intersect_assoc() is that array_intersect_uassoc() function uses a user defined function to find the intersecting array elements.

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

In the above syntax values and keys of "array1" is compared with other arrays, and in the function only the keys are checked in the array. Both Keys and values from "array1" is displayed.

    <?php
    function funct1($v1,$v2) 
    {
     if ($v1==$v2)
	{
	return 0;
	}
     if ($v1>$v2)
	{
	return 1;
	}
     else
	{
	return -1;
	}
     }
     $a=array(0=>"One",1=>"Two",2=>"Three");
     $b=array(3=>"One",1=>"Two",5=>"Three");
     print_r(array_intersect_uassoc($a,$b,"funct1"));
     ?>

   Array ( [1]=> Two )

In the above example the two arrays "$a", "$b" are compared for keys and values automatically, then checks for the keys alone in the function which returns "Two" in an array.