/*
* 二維數組自定義排序函數
* uasort($arr,function_name)
*
**/
$arr = array(
  array('a'=>1,'b'=>'c'),
  array('a'=>4,'b'=>'a'),
  array('a'=>5,'b'=>'g'),
  array('a'=>7,'b'=>'f'),
  array('a'=>6,'b'=>'e')
);
function compare_arr($x,$y){
  if($x['b']<$y['b']){
    return -1;
  }else if($x['b']>$y['b']){
    return 1;
  }else{
    return 0;
  }
}
uasort($arr,'compare_arr');
foreach($arr as $a){
  echo $a['a'].'=>'.$a['b'].'<br/>';
}

class multiSort
{
   var $key;  //key in your array
   //排序函數 參數依次是 數組 待排列索引 排序類型
   function run ($myarray, $key_to_sort, $type_of_sort = '')
   {
     $this->key = $key_to_sort;
     if ($type_of_sort == 'desc')
       uasort($myarray, array($this, 'myreverse_compare'));
     else
       uasort($myarray, array($this, 'mycompare'));
     return $myarray;
   }
   //正序
   function mycompare($x, $y)
   {
     if ( $x[$this->key] == $y[$this->key] )
       return 0;
     else if ( $x[$this->key] < $y[$this->key] )
       return -1;
     else
       return 1;
   }
   //逆序
   function myreverse_compare($x, $y)
   {
     if ( $x[$this->key] == $y[$this->key] )
       return 0;
     else if ( $x[$this->key] > $y[$this->key] )
       return -1;
     else
       return 1;
   }
}