检查PHP会话是否已经开始 [英] Check if PHP session has already started

问题描述

我有一个PHP文件，有时从启动会话的页面调用该文件，有时从没有会话启动的页面调用.因此，当我在该脚本上使用session_start()时，有时会收到会话已开始"的错误消息.为此，我将这些行放在上面:

I have a PHP file that is sometimes called from a page that has started a session and sometimes from a page that doesn't have session started. Therefore when I have session_start() on this script I sometimes get the error message for "session already started". For that I've put these lines:

if(!isset($_COOKIE["PHPSESSID"]))
{
  session_start();
}

但是这次我收到了以下警告消息:

but this time I got this warning message:

注意:未定义变量:_SESSION

Notice: Undefined variable: _SESSION

有没有更好的方法来检查会话是否已经开始?

Is there a better way to check if session has already started?

如果我使用@session_start，它将使一切正常运行，只是关闭警告?

If I use @session_start will it make things work properly and just shut up the warnings?

推荐答案

PHP> = 5.4.0，PHP 7

if (session_status() == PHP_SESSION_NONE) {
    session_start();
}

参考: http://www.php.net/manual/zh/function.session-status.php

对于 PHP< 5.4.0

if(session_id() == '') {
    session_start();
}

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