PHP 数组函数 array_intersect_ukey()

<?php
   function key_compare_func($k1, $k2) {
      if ($k1 == $k2)
         return 0;

      else if ($k1 > $k2)
         return 1;

      else
         return -1;
   }

   $input1 = array('blue'=>1, 'red'=>2, 'green'=>3, 'purple'=>4);
   $input2 = array('green'=>5, 'blue'=>6, 'pink'=>7, 'black'=>8);

   $result = array_intersect_ukey($input1, $input2, "key_compare_func");
   var_dump($result);
?>