我只需要调试生产php网站中的问题。这是原始开发人员假定$ cust_id = $ _SESSION ['cust_id'];的演示。是通过值传递的，但是以某种方式它是对会话对象的引用！

有人可以解释以下行为及其背后的原因，以及以后PHP开发人员可以做什么以免再次犯此错误。

代码：

<?php

        session_start();

        $_SESSION['cust_id'] = 1;           // sets $_SESSION['cust_id'] 1 = all good

        echo $_SESSION['cust_id'] . "<br>";    // returns 1 = all good

        $cust_id = $_SESSION['cust_id'];      // sets $cust_id 1 = all good     //note this is not =&

        echo $cust_id . "<br>";               // returns 1 = all good

        echo $_SESSION['cust_id'] . "<br>";    // returns 1 = all good

        $cust_id = 5;                          // He is going to use this variable for something else for a little bit. should be ok.

        echo $cust_id . "<br>";               // returns 5 = all good

        echo $_SESSION['cust_id'] . "<br>";    // He expected this to still hold 1,because he haden't changed the session variable at all
                                               // returns 5!!!  what the...  $cust_id wasn't a reference to the session object surely? the original developer didn't expect that.

        echo "phpversion: " . phpversion() . "<br>";

        echo "ini_get('register_globals'): " . ini_get('register_globals') . "<br>";

输出：

1
1
1
5
5
phpversion: 5.3.29
ini_get('register_globals'): 1