二维数组根据某个字段排序

<?php  
/** 
 * 二维数组根据某个字段排序 
 * 功能：按照用户的年龄倒序排序 
 * @author ruxing.li 
 */  
header('Content-Type:text/html;Charset=utf-8');  
$arrUsers = array(  
    array(  
            'id'   => 1,  
            'name' => '张三',  
            'age'  => 25,  
    ),  
    array(  
            'id'   => 2,  
            'name' => '李四',  
            'age'  => 23,  
    ),  
    array(  
            'id'   => 3,  
            'name' => '王五',  
            'age'  => 40,  
    ),  
    array(  
            'id'   => 4,  
            'name' => '赵六',  
            'age'  => 31,  
    ),  
    array(  
            'id'   => 5,  
            'name' => '黄七',  
            'age'  => 20,  
    ),  
);   
  
  
$sort = array(  
        'direction' => 'SORT_DESC', //排序顺序标志 SORT_DESC 降序；SORT_ASC 升序  
        'field'     => 'age',       //排序字段  
);  
$arrSort = array();  
foreach($arrUsers AS $uniqid => $row){  
    foreach($row AS $key=>$value){  
        $arrSort[$key][$uniqid] = $value;  
    }  
}  
if($sort['direction']){  
    array_multisort($arrSort[$sort['field']], constant($sort['direction']), $arrUsers);  
}  
  
var_dump($arrUsers);  
  
/* 
输出结果： 
 
array (size=5) 
  0 =>  
    array (size=3) 
      'id' => int 5 
      'name' => string '黄七' (length=6) 
      'age' => int 20 
  1 =>  
    array (size=3) 
      'id' => int 2 
      'name' => string '李四' (length=6) 
      'age' => int 23 
  2 =>  
    array (size=3) 
      'id' => int 1 
      'name' => string '张三' (length=6) 
      'age' => int 25 
  3 =>  
    array (size=3) 
      'id' => int 4 
      'name' => string '赵六' (length=6) 
      'age' => int 31 
  4 =>  
    array (size=3) 
      'id' => int 3 
      'name' => string '王五' (length=6) 
      'age' => int 40 
 
*/