警告:无法修改标头信息-标头已由(输出)发送


Warning: Cannot modify header information - headers already sent by (output)

我一次又一次地遇到这个错误,我尝试了一切,但找不到解决方案

警告:无法修改标题信息-标题已由第93行/home/pappu/public_html/forum/index.php中的/home/xxxxx/xxxx/forum/index.php:90开始输出

这是我的index.php代码

<?php
include_once("connect.php");
session_start();
?>
<html>
<head>
<title>MyForum</title>
<style type="text/css">
body {
background-color: #333;
margin-top: 150px;
margin-right: 0px;
margin-bottom: 0px;
margin-left: 0px;
}
.content {
background-color: #666;
width: 960px;
margin-right: auto;
margin-left: auto;
border-radius: 3px;
-webkit-border-radius: 3px;
-moz-border-radius: 3px;
padding: 20px;
}
.content .categories {
width: 700px;
background-color: #333;
border-radius: 3px;
-webkit-border-radius: 3px;
-moz-border-radius: 3px;
margin: 0px;
font-family: "Trebuchet MS", Arial, Helvetica, sans-serif;
color: #FFF;
}
.categories .community_heading {
font-family: "Trebuchet MS", Arial, Helvetica, sans-serif;
font-variant: normal;
text-transform: capitalize;
color: #CCC;
margin: 0px;
padding-top: 7px;
padding-right: 7px;
padding-bottom: 7px;
padding-left: 14px;
font-size: 18px;
font-weight: bold;
}
.content .categories hr {
background-color: #666;
height: 3px;
border: 0px;
width: 700px;
margin: 0px;
}
.content .categories .cat_links {
border-bottom-width: thin;
border-bottom-style: solid;
border-bottom-color: #000;
padding-top: 7px;
padding-right: 7px;
padding-bottom: 7px;
padding-left: 14px;
font-size: 14px;
color: #000;
}
.content .categories .cat_a {
font-family: "Trebuchet MS", Arial, Helvetica, sans-serif;
font-size: 18px;
font-variant: normal;
text-transform: capitalize;
color: #777;
text-decoration: none;
}
.content .categories .cat_a:hover {
text-decoration: underline;
color: #DDD;
}
.content .categories .desc {
margin: 0px;
font-family: "Trebuchet MS", Arial, Helvetica, sans-serif;
font-size: 12px;
font-weight: bold;
color: #CCC;
}
</style>
</head>
<body>
<?php
if(!isset($_SESSION['password']))
{
include_once("Location:header.php");
}
else
{
header("Location:member.php");
}
?>
<div class="content">
<div class="categories">
<h3 class="community_heading">Community</h3>
<hr />
<?php
$query = "SELECT * FROM categories ORDER BY cat_id ASC";
$result = mysql_query($query) or die(mysql_error());
$categories = "";
if(mysql_num_rows($result) > 0 )
{
while($row = mysql_fetch_array($result))
{
$cat_id = $row['cat_id'];
$cat_title = $row['cat_title'];
$cat_desc = $row['cat_description'];
$categories .="
<div class='cat_links'>
<a href='view_category?cid=".$cat_id."' class='cat_a'>$cat_title</a>
<p class='desc'>$cat_desc</p>
</div>";
}
echo $categories ;
}
else 
{
}
?>
</div>
</div>
</body>
</html>

在包含输出到页面的ANY代码后,不能调用Header()。您需要重写正在执行的操作,以便Header()调用高于所有HTML代码。