警告:无法修改标头信息 - 标头已发送

问题描述

可能的重复:
PHP 已经发送的标头

当我成功登录一个页面时，我收到有关标题已发送"的错误消息.

I'm getting errors about "headers already sent" when I successfully log into a page.

这是我处理登录的代码:

Here's my code that deals with the login:

<?php
include("config.php");
$eUsername = $_POST['username'];
$ePassword = $_POST['password'];

$con = mysql_connect("localhost","MY_USERNAME","MY_PASSWORD");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

mysql_select_db("forum", $con);
$result = mysql_query("SELECT * FROM members WHERE username = '$eUsername'");

while($row = mysql_fetch_array($result))
  {
    if ($ePassword==$row['password']) {
      echo "Correct";
       setcookie("loggedIn", "true", time()+1000000000);
       setcookie("logUsername", "$eUsername", time()+100000000);
       setcookie("logPassword", "$ePassword", time()+100000000);
    }
    else {
      echo "Incorrect username/password.  Please try again.";
    }
  }
mysql_close($con);
if ($_COOKIE['loggedIn']=="true") {
$curURL=basename($_SERVER['SCRIPT_NAME']);
echo "You are already logged in.  <a href='$curURL?lo=true'>Log out?</a>";
}
echo "<br /><br />";
print_r($_COOKIE);
?>

所以基本上它的作用是如果您使用正确的信息登录，它会设置三个 cookie，您的用户名、密码和一个来检查其他两个.

So basically what this does is if you log in with the correct information, it will set three cookies, your username, password and one to check for the other two.

但是当我成功登录时，出现以下错误:

But when I do log in successfully, I get these errors:

警告:无法修改标题信息 - 标题已由(输出开始于/home/scott/web/forum/index.php:18)在/home/scott/web/forum/index.php 中第 19 行发送

Warning: Cannot modify header information - headers already sent by (output started at /home/scott/web/forum/index.php:18) in /home/scott/web/forum/index.php on line 19

警告:无法修改标题信息 - 标题已由(输出开始于/home/scott/web/forum/index.php:18)在/home/scott/web/forum/index.php 第 20 行

Warning: Cannot modify header information - headers already sent by (output started at /home/scott/web/forum/index.php:18) in /home/scott/web/forum/index.php on line 20

警告:无法修改标题信息 - 标题已由(输出开始于/home/scott/web/forum/index.php:18)在第 21 行的/home/scott/web/forum/index.php 中发送

Warning: Cannot modify header information - headers already sent by (output started at /home/scott/web/forum/index.php:18) in /home/scott/web/forum/index.php on line 21

我做错了什么?

推荐答案

您有一个回声，它可能在您的 setcookie 调用之前发生.

You've got an echo which could occur before your setcookie call.

header 或 setcookie 或任何其他发送 HTTP 标头的内容必须在任何其他输出之前完成，否则您将收到警告/错误.

header or setcookie or anything else that sends HTTP headers has to be done before any other output, or you'll get that warning/error.

此外，您应该检查 config.php 以确保在关闭 ?> php 标记之后没有尾随空格.请记住...任何未包含在 <?php ... ?> 中的内容都被 php 解析器视为输出，并且会被回显"出来.

Also, you should check config.php to make sure there's no trailing whitespace after the closing ?> php tag. Remember... anything not inluded in <?php ... ?> is considered output by the php parser, and will get "echo'd" out.

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