php怎么判断是不是二维数组

//定义一般数组
$num = array(1,2,3,4,5);
//定义关联数组
$user = array("name"=>"Tom","age"=>20,"gender"=>"male");

//使用array表示法初始化二维数组
$users = array(
              array("name"=>"Tom","age"=>20,"gender"=>"male"),
              array("name"=>"Lucy","age"=>22,"gender"=>"female"),
              array("name"=>"Jack","age"=>18,"gender"=>"male")
          );

//使用简单的方式初始化
$users[0] = array("name"=>"Tom","age"=>20,"gender"=>"male");
$users[1] = array("name"=>"Lucy","age"=>22,"gender"=>"female");
$users[2] = array("name"=>"Jack","age"=>18,"gender"=>"male");

//使用普通数组定义二维数组
$users = array(
              ["name"=>"Tom","age"=>20,"gender"=>"male"],
              ["name"=>"Lucy","age"=>22,"gender"=>"female"],
              ["name"=>"Jack","age"=>18,"gender"=>"male"]
          );

function is_two_dimen_array($arr){
    //判断是否为数组
    if(is_array($arr)){
        foreach($arr as $v){
            if(!is_array($v)){
                //如果数组中每个元素不是数组
                return false;
            }
        }
        //如果每个元素都是数组，返回真
        return true; 
    }
    //如果不是数组，返回假
    return false;
}

//测试
$array = array(array(1,2),array(3,4));
var_dump(is_two_dimen_array($array)); //输出bool(true)

/**
 * 判断是否为二维数组
 * @param $arr 待判断的数组
 * @return bool
 */
function is_two_dimen_array($arr){
    //筛选该数组中元素不是数组的元素
    $result = array_filter($arr,"is_array");
    //对筛选出的元素应用array_filter()函数，判断是否还存在不是数组的元素
    $result = array_map("is_array",$result);
    //如果存在该数组中的元素不是数组，返回false，否则返回true
    return !(bool)array_sum($result);
}

//测试
$array = array(array(1,2),array(3,4));
var_dump(is_two_dimen_array($array)); //输出bool(true)