<?php
function myfunction($a,$b)
{
if ($a===$b)
&nbsp;&nbsp;  {
&nbsp;&nbsp;  return 0;
&nbsp;&nbsp;  }
&nbsp;&nbsp;  return ($a>$b)?1:-1;
}

$a1=array("a"=>"red","b"=>"green","c"=>"blue");
$a2=array("a"=>"black","b"=>"yellow","d"=>"brown");
$a3=array("e"=>"purple","f"=>"white","a"=>"gold");

$result=array_intersect_ukey($a1,$a2,$a3,"myfunction");
print_r($result);
?>