php5.6 无法获取会话变量，然后删除该变量 [英] php5.6 cannot fetch a session variable and THEN delete the variable

问题描述

今天我有点奇怪.

我发现显然我不能使用会话变量然后销毁它(而不破坏整个会话.)

让我解释一下.如果我这样做，例如:

<预><代码>如果(isset($_SESSION['var'])){$var = $_SESSION['var'];未设置($_SESSION['var'])；}var_dump($_SESSION);echo "var: $var";

结果是 $var 和键都是 $_SESSION 的 "var" 都是空的.

但是，如果您注释掉取消设置的部分，则 var 将同时出现在 $var 和 $_SESSION 数组中.

即使是更狂热的人:

if (isset($_SESSION['var'])) {$var = array_splice($_SESSION, array_search('var', array_keys($_SESSION)), 1);}

似乎有完全相同的问题.

这太奇怪了.

当我遇到这种糟糕的行为时，我该怎么办?

提前致谢.

我只是做了明显的明智之举:

$session_copy = $_SESSION;如果(isset($session_copy['var'])){$var = $session_copy['var'];未设置($_SESSION['var'])；}

是的，也不起作用.

解决方案

这在 php 文档中得到了回答:https://www.php.net/manual/en/reserved.variables.session.php#85448

<块引用>

请注意，如果您将 register_globals 设置为 On，全局变量与 $_SESSION 变量关联的是引用，因此这可能会导致一些奇怪的情况.

这是一个奇怪的情况，但并非没有记录.如果您想更多地了解 php 为何以这种方式处理会话变量，我相信您可以进一步挖掘.

Today I have a bit of an odd one.

I have found out that apparently I cannot use a session variable AND THEN destroy it (without destroying the entire session.)

Let me explain. If I do this, for example:

if (isset($_SESSION['var'])) {
    $var = $_SESSION['var'];
    unset($_SESSION['var']);
}
var_dump($_SESSION);
echo "var: $var";

The result is "var" is empty both as $var and as a key is $_SESSION.

However, if you comment out the unsetting part, the var is in both $var as well as in the $_SESSION array.

even the much fancier:

if (isset($_SESSION['var'])) {
    $var = array_splice($_SESSION, array_search('var', array_keys($_SESSION)), 1);   
}

seems to have the exact same problem.

This is sooooo odd.

What can I even do when presented with such a weeeeiiird behavior?

Thank you in advance.

EDIT: I just did the obvious wise-ass thing to do:

$session_copy = $_SESSION;

if (isset($session_copy['var'])) {
    $var = $session_copy['var'];
    unset($_SESSION['var']);
}

Yep, doesn't work either.

解决方案

This is answered in the php docs here: https://www.php.net/manual/en/reserved.variables.session.php#85448

Please note that if you have register_globals to On, global variables associated to $_SESSION variables are references, so this may lead to some weird situations.

It is a weird situation, but not undocumented. I'm sure you can dig further if you want to know more about why php handles session variables this way.

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