uasort ( array,cmp_function )

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

   input = array("d"=>"lemon", "a"=>"orange", "b"=>"banana" );
   uasort(input, "cmp_function");

   print_r($input);
?>

Array ( [a] => orange [d] => lemon [b] => banana )