我遇到了问题..
输出错误：无法修改标题信息..
原因是什么？我怎么能解决它.. 感谢您的帮助..我已经检查了所有，但是我仍然无法修复它。会出现什么问题？
以下是我的代码：
<!DOCTYPE html>
<html dir="ltr" lang="en-US"><head><!-- Created by Artisteer v4.3.0.60747 -->
<meta charset="utf-8">
<title>Home</title>
<meta name="viewport" content="initial-scale = 1.0, maximum-scale = 1.0, user-scalable = no, width = device-width">
<link rel="stylesheet" href="style.css" media="screen">
<link rel="stylesheet" href="style.responsive.css" media="all">
<link rel="stylesheet" type="text/css" href="http://fonts.googleapis.com/css?family=Salsa|PT+Sans&subset=latin">
<script src="jquery.js"></script>
<script src="script.js"></script>
<script src="script.responsive.js"></script>
<script>jQuery(function ($) {
'use strict';
if ($.fn.themeSlider) {
$(".art-slidecontainera65d557e889141cb8638b82feda1c335").each(function () {
var slideContainer = $(this), tmp;
var inner = $(".art-slider-inner", slideContainer);
inner.children().filter("script").remove();
var helper = null;
if ($.support.themeTransition) {
helper = new BackgroundHelper();
helper.init("fade", "next", $(".art-slide-item", inner).first().css($.support.themeTransition.prefix + "transition-duration"));
inner.children().each(function () {
helper.processSlide($(this));
});
} else if (browser.ie && browser.version <= 8) {
var slidesInfo = {
".art-slidea65d557e889141cb8638b82feda1c3350": {
"bgimage" : "url('images/slidea65d557e889141cb8638b82feda1c3350.jpg')",
"bgposition": "0 0",
"images": "",
"positions": ""
},
".art-slidea65d557e889141cb8638b82feda1c3351": {
"bgimage" : "url('images/slidea65d557e889141cb8638b82feda1c3351.jpg')",
"bgposition": "0 0",
"images": "",
"positions": ""
}
};
$.each(slidesInfo, function(selector, info) {
processElementMultiplyBg(slideContainer.find(selector), info);
});
}
inner.children().eq(0).addClass("active");
slideContainer.themeSlider({
pause: 2600,
speed: 600,
repeat: true,
animation: "fade",
direction: "next",
navigator: slideContainer.siblings(".art-slidenavigatora65d557e889141cb8638b82feda1c335"),
helper: helper
});
});
}
});
</script></head>
<body>
<div id="art-main">
<header class="art-header">
<div class="art-shapes">
</div>
<h1 class="art-headline">
<a href="index.php">FPES</a>
</h1>
<h2 class="art-slogan">Faculty Performance Evaluation System.</h2>
<?php
//connect to the database
$connect = mysql_connect("localhost","root","");
mysql_select_db("db_fpes",$connect); //select the table
if(isset($_POST['btn_submit'])){
$username = $_POST['username'];
$password = $_POST['pass'];
$result = mysql_query ("SELECT * FROM professors where fac_stat = 1 and Faculty_code = '".$username."' and Faculty_code = '".$password."' ");
if($username == 'admin' && $password == 'admin' && mysql_num_rows($result) == 0 ){
header('Location: admin/home.php'); die;
}
else
{
$row = mysql_fetch_assoc($result);
if($row['system_user'] == 1){
header('Location: Grading/index.php'); die;
}
else if($row['system_user'] == 2){
header('Location: Secretary/home.php'); die;
}
else
header('Location: index.php'); die;
}
}
?>
<nav class="art-nav">
<ul class="art-hmenu"><li><a href="home.html" class="active">Home</a></li>
<li><a href="add-profile.html">About Us</a></li>
</ul>
</nav>
</header>
<div class="art-sheet clearfix">
<div class="art-layout-wrapper">
<div class="art-content-layout">
<div class="art-content-layout-row">
<div class="art-layout-cell art-content"><article class="art-post art-article">
<div class="art-postcontent art-postcontent-0 clearfix"><div class="art-content-layout-wrapper layout-item-0">
<div class="art-content-layout layout-item-1">
<div class="art-content-layout-row">
<div class="art-layout-cell layout-item-2" style="width: 100%" >
<p></p><div id="a65d557e889141cb8638b82feda1c335" style="position: relative; display: inline-block; z-index: 0; margin: 0px; border-width: 0px; " class="art-collage">
<div class="art-slider art-slidecontainera65d557e889141cb8638b82feda1c335" data-width="900" data-height="287">
<div class="art-slider-inner">
<div class="art-slide-item art-slidea65d557e889141cb8638b82feda1c3350" >
</div>
<div class="art-slide-item art-slidea65d557e889141cb8638b82feda1c3351" >
</div>
</div>
</div>
<div class="art-slidenavigator art-slidenavigatora65d557e889141cb8638b82feda1c335" data-left="1" data-top="1">
<a href="#" class="art-slidenavigatoritem"></a><a href="#" class="art-slidenavigatoritem"></a>
</div>
</div>
<p>
</p><p>
</p>
</div>
</div>
</div>
</div>
<div class="art-content-layout layout-item-1">
<div class="art-content-layout-row">
<div class="art-layout-cell layout-item-3" style="width: 67%" >
<h2><span style="color: rgb(128, 0, 0); line-height: 51px; font-size: 40px;">Welcome </span><span style="color: rgb(108, 127, 147); line-height: 31px; font-size: 28px;">to our site!</span></h2>
<h3><img width="250" height="195" alt="" src="images/1037312_small500.jpg" style="float: left; margin-right: 15px;" class="">Performance Faculty Evalutaion System. </h3>
<p>Insert Description Here!.<br></p>
</div>
<div class="art-layout-cell layout-item-4" style="width: 33%" >
<form method = "post" action = "">
<h1>Please Login<br></h1><p style="margin-top: 10px;"> Username: <input type="text" name = "username" > </p><p>
<p> Password: <input type="text" name = "pass"></p><p style="text-align: right;">
<input type = "submit" name = "btn_submit" class="art-button" value = "Login"/><br></p>
</form>
</div>
</div>
</div>
</article></div>
</div>
</div>
</div>
</div>
<footer class="art-footer">
<div class="art-footer-inner">
<p>GoMiracles © 2014 - 2015. All Rights Reserved.<br></p>
</div>
</footer>
</div>
</body></html>
答案 0 :(得分：1)
Headers already sent是一个问题，您尝试使用header()重定向用户，或者当您尝试在浏览器已呈现内容时启动会话session_start()时（例如html，但可以）例如，也是一个PHP echo语句。
要解决此问题，请在发送标头之前检查您是否有任何echo()语句或原始HTML，并检查<?php前面是否有空格。
可以在此处找到帮助您解决此问题的更详细答案：https://stackoverflow.com/a/8028987/4274852
我怀疑您没有向我们提供您的所有代码，因为我目前无法找到您的任何具体问题。我希望上面的链接可以帮助您调试代码，如果没有：确保在PHP代码上面发布所有内容。
请注意：我发现您仍在使用mysql_query语句，这些语句已被弃用。请改用msqli或PDO。
修改
我看到你发布了你的代码，尝试替换页面顶部的所有PHP代码而不是中间代码，它应该可以工作。在当前代码中，您在PHP代码之前有原始HTML（在这种情况下为<h1>和<p>元素），这使得无法使用header()发送更多标头数据，因为所有标头在呈现页面之前已经发送过。
我编辑了你的代码来解决这个问题，希望你可以在这里找到它（而不是在这里发布，这会产生一个尴尬的长答案）：