不靠谱的 array_diff ！！

原来不是对应键比对，是我理解错了

        $a1 = array(
            'zipcode' => '2',
            'remark' => '',
        );

        $a2 = array(
            'zipcode' => '',
            'remark' => '3332',
        );
        echo '<pre>';
        print_r(array_diff($a1, $a2));
        exit;

输出

Array
(
[zipcode] => 2
)

        $a1 = array(
            'zipcode' => '',
            'remark' => '',
        );

        $a2 = array(
            'zipcode' => '',
            'remark' => '3332',
        );

        echo '<pre>';
        print_r(array_diff($a1, $a2));
        exit;

输出

Array
(
)

什么鬼，好像不是自己预期的啊！