例子

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

$arr = array("Peter", "glenn","Cleveland","peter","cleveland", "Glenn");

usort($arr, "my_sort");

print_r ($arr);
?>  

輸出：

Array
(
[0] => peter
[1] => glenn
[2] => cleveland
[3] => Peter
[4] => Glenn
[5] => Cleveland
)