php - session_start();echo SID;刷新时输出空白页？

Question

当我第一次运行这段代码时

<?php
session_start();
echo SID;
?>

，我得到一些类似的东西:

PHPSESSID=9o2bhrqmln2j52caspdhholhk7

但是当我刷新时我得到一个空白页

直到我删除 PHPSESSION cookie 并开始一个新的……这是正常的还是我有问题？

Answer 1

The manual说:

Alternatively, you can use the constant SID which is defined if the session started. If the client did not send an appropriate session cookie, it has the form session_name=session_id. Otherwise, it expands to an empty string. Thus, you can embed it unconditionally into URLs.

它并不意味着包含 session ID，它意味着在禁用 cookie 时附加到 URL。