PHP json_decode深度参数不起作用 [英] PHP json_decode depth parameter doesn't work

问题描述

PHP的json_decode函数具有一个"depth"参数，您可以在其中指定递归的深度.但是下面的代码:

PHP's json_decode function has a "depth" parameter, where you can specify how deep it will recurse. But the following code:

test = array(
    'name' => 'sean',
    'dob' => '12-20',
    'parents' => array(
        'father' => 'tommy',
        'mother' => 'darcy'
    )
);

foreach(range(1, 3) as $depth) {
    echo "-----------------\n depth: $depth\n";
    print_r(json_decode(json_encode($test), true, $depth));
}

产生此输出:

-----------------
 depth: 1
-----------------
 depth: 2
-----------------
 depth: 3
Array
(
    [name] => sean
    [dob] => 12-20
    [parents] => Array
        (
            [father] => tommy
            [mother] => darcy
        )

)

我期望的是，深度为1时显示姓名"和"dob"，深度为2时也显示父母.我不明白为什么1或2的深度根本不显示任何内容.

What I would expect is a depth of 1 to show "name" and "dob", and a depth of 2 to show the parents, also. I don't get why a depth of 1 or 2 displays nothing at all.

任何人都可以向我解释我不了解的内容吗?

Can anyone explain to me what I'm not understanding?

推荐答案

文档说明原因.

如果无法解码json，则返回

NULL；如果编码数据的深度大于递归限制，则返回.

NULL is returned if the json cannot be decoded or if the encoded data is deeper than the recursion limit.

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