php简单的数组递归

<?php
$arr = array(
    'zz'=>1,
    'aa' =>  array(
        'bb' => array(
            'id'=>5,
            'grade'=>5,
            'a'=>111
        ),
        'cc' =>  array(
            array(
                "name"=>'some',
                "a"=>999
            )
        ),
        'dd' =>  array(
            'ctime'=>1001
        )
    ),
    'ee' =>  array(
        'ff' =>array(
            'age'=> 25,
            'sex'=>1
        )
    )
);
function ToUrlParams($arr,&$data=array()){
    global $str;
    ksort($arr);
    if(!is_array($arr)){
        echo $arr."不是数组";
    }else{
        foreach($arr as $k=>$v){
            if(is_array($v)){
                ksort($v);
                ToUrlParams($v);
            }else{
               $str .= $k.'='.$v.'&';
            }
        }
    }
    return substr($str,0,strlen($str)-1);
}
$str = ToUrlParams($arr);
echo $str;
输出：
a=111&grade=5&id=5&a=999&name=some&ctime=1001&age=25&sex=1&zz=1
?>