php 无法发送会话 cookie - 标头已发送
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Cannot send session cookie - headers already sent
提问by Andrej
Possible Duplicate:
Headers already sent by PHP
可能重复：
PHP 已发送的标头
Below is a simple example of my PHP code which (I hope so) is self explanatory. What I try to do is to update the session variable. But the output of the script is as follows:
下面是我的 PHP 代码的一个简单示例（我希望如此）是不言自明的。我尝试做的是更新会话变量。但是脚本的输出如下：
Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /Library/WebServer/Documents/facebook/test.php:8) in /Library/WebServer/Documents/facebook/test.php on line 11
警告：session_start() [function.session-start]：无法发送会话 cookie - 头文件已由 /Library/WebServer/Documents/facebook 中的（输出开始于 /Library/WebServer/Documents/facebook/test.php:8）发送/test.php 第 11 行
The warning is caused by the echostatements in line 8 and 9, of course. Is there any simple solution to stop this warning.
当然，警告是由第echo8 行和第 9 行中的语句引起的。是否有任何简单的解决方案来阻止此警告。
Thanks for any pointers, Andrej
感谢您的指点，安德烈
<?php
session_start();
$_SESSION['percent'] = 0;
$iterations = 50;
for ($i = 0; $i <= iterations; $i++) {
$percent = ($i / $iterations) * 100;
echo "Hello World!";
echo "<br />";
// update session variable
session_start();
$_SESSION['percent'] = number_format($percent, 0, '', '');
session_commit();
}
?>
The only solution that works (i.e. updates the session variable) for me is:
对我来说唯一有效的解决方案（即更新会话变量）是：
<?php
ob_start();
session_start();
$_SESSION['percent'] = 0;
$iterations = 50;
for ($i = 0; $i <= 50; $i++) {
$percent = ($i / $iterations) * 100;
echo "Hello World!";
echo "<br />";
// update session variable
session_start();
$_SESSION['percent'] = number_format($percent, 0, '', '');
session_commit();
}
ob_flush();
?>
It's ugly, while it buffers the output first...
这很丑陋，而它首先缓冲输出......
采纳答案by b7kich
It's not possible to set cookies (or send any other headers) after output is started. You could add ob_start() at line 1 to buffer the output.
输出开始后无法设置 cookie（或发送任何其他标头）。您可以在第 1 行添加 ob_start() 以缓冲输出。
The right solution is to separate logic from the output. Check out e.g. http://www.paragoncorporation.com/ArticleDetail.aspx?ArticleID=21
正确的解决方案是将逻辑与输出分开。查看例如 http://www.paragoncorporation.com/ArticleDetail.aspx?ArticleID=21
回答by James
Remove the session_start() from inside the for loop.
从 for 循环内部删除 session_start()。
Put the session_commit() outside the for loop at the very end.
最后将 session_commit() 放在 for 循环之外。
Both these functions should only be called once in a script.
这两个函数只能在脚本中调用一次。
回答by dudi
If you don't have any previeus output before the session-start() statement,then try to resave your .php file as an ansi-file or as utf-8 without BOM file. that's bc in some cases the editor itself writes things as an output in the file.
如果您在 session-start() 语句之前没有任何 previeus 输出，那么尝试将您的 .php 文件重新保存为 ansi-file 或 utf-8 没有 BOM 文件。那是 bc 在某些情况下，编辑器本身将内容作为输出写入文件。
It worked for me
它对我有用
回答by Sarah
As the others have stated, the cause of the error is the second session_start()you are using. However, the actual reason it's throwing an error is because you are trying to set a header after you've already sent output. Since the session_start() function sets the session cookie, it tried to set the cookie header, which is after you already echo content.
正如其他人所说，错误的原因是session_start()您使用的第二个。但是，它引发错误的实际原因是因为您在已经发送输出后尝试设置标头。由于 session_start() 函数设置会话 cookie，它尝试设置 cookie 标头，这是在您已经回显内容之后。
回答by svens
You have to execute the session_start()function only once. So just drop the one within the loop.
您只需执行session_start()一次该功能。因此，只需将循环中的一个删除即可。
Also you don't have to do the session_commit()manually, in most cases PHP handles this for you automatically.
此外，您不必session_commit()手动执行此操作，在大多数情况下，PHP 会自动为您处理。
