Question

可能重复：
  Cannot modify header information - headers already sent, Why its happening
  Headers already sent by PHP

我网站上的所有页面都出错。

 Warning: Cannot modify header information - headers already sent by (output started at        
    /home/payaim/public_html/directyourmoney/common.htm:3) in /home/payaim/public_html/directyourmoney/common.htm on line 75

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /home/payaim/public_html/directyourmoney/common.htm:3) in /home/payaim/public_html/directyourmoney/common.htm on line 5228

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/payaim/public_html/directyourmoney/common.htm:3) in /home/payaim/public_html/directyourmoney/common.htm on line 5228

Warning: Cannot modify header information - headers already sent by (output started at /home/payaim/public_html/directyourmoney/common.htm:3) in /home/payaim/public_html/directyourmoney/common.htm on line 5232

Warning: Cannot modify header information - headers already sent by (output started at /home/payaim/public_html/directyourmoney/common.htm:3) in /home/payaim/public_html/directyourmoney/common.htm on line 5272

警告上面是我网站上的所有页面。我删除了反映标题标签的空格和回声，我也搜索过但没有运气。请帮帮我。

Answer 1

如果您需要更具体的帮助，请提供您的代码。

但是，这意味着您尝试修改标题（例如使用header函数或setcookie一个`之后您已经发送了一些html行。这不是允许的。

在您的情况下，您正在尝试启动新会话，此操作需要发送cookie。这就是为什么在documentation中明确说明如果您要开始新会话，则应在页面顶部添加session_start。

如果要修改标题，则必须先打印标题。

Answer 2

在任何html输出之后你不能使用session_start()

这将有效：

<?php
    session_start();
    $some_value = 'something';
?>

这将不工作：

<?php
    $some_value = 'something';

    echo $some_value;

    session_start();
?>

Answer 3

以下内容可能会导致您发布的问题......

<html>
<head>
<title>blah</title>
<body>
    <?php

            session_start();
        header("Location: http://www.google.com");
        exit();
    ?>
</body>
</html>

或作为Matei Mihai说的

<?php
    $some_value = 'something';

    echo $some_value;

    session_start();
?>

警告：无法修改标头信息 - 已发送的标头

3 个答案: