Cannot Modify Header Information

connormcwood · 08-28-2012, 04:00 AM

Hello people of codingforums I am having a problem with this "Cannot Modify Header Information". I know that extra blank lines can cause this problem but I just can't see where they are. They're bugging me an if you login here, you will receive the error. I dont seem to have this error on localhost but on my website I do?

This is the error:

Quote:

Warning: Cannot modify header information - headers already sent by (output started at /home/connor/public_html/game/includes/top.php:11) in /home/connor/public_html/game/login.php on line 18

Top.php:

Code:

<? 
if(session_id() == ""){ session_start(); } 
?><html><head>
<link rel="icon" href="images/favicon.ico" type="image/x-icon">
<title> Cyber States - A online state simulation game.</title>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<LINK REL=stylesheet HREF="style.css" TYPE="text/css">
<meta name="robots" content="all">
<meta name="revisit-after" content="7 days">
<meta name="author" content="connor mcgarty-wood">
<meta name="keywords" content="games, gaming, cyber, states, cyberstates, simulation, simulate, online, top, 100, interesting, internet, bored, game, windows, browser game, browser">
<meta name="description" content="A online simulation game built on the topic of owning your own state. It is online
and you simulate everyday and collect taxes. This is a very interesting simulation browser games.">
</head>
<body>
<div id="header">
<img src="images/cyberstates.jpg" ALT="Cyberstates">
</div>
<center>
/* adds */
</center>
<br />

Login.php

Code:

<? 
include('includes/top.php');
include('includes/menu.php'); 
$error="";
if(isset($_SESSION['username'])){
header('location:default.php');
}
if(isset($_POST['login'])) {
include('includes/connect.php');
$username = $_POST['username'];
$password = md5($_POST['password']);
$query = "select * from users where username='$username' and password='$password'";
$result = mysql_query($query);
if (mysql_num_rows($result) != 1) {
$error = "Your username or password was Incorrect.";
} else {
    $_SESSION['username'] = $_POST['username'];
	header('Location: loggedin.php');
} } 
?>
<div id="rightbox">
<H2>Login</H2>
<? 
if(!$error == ""){
echo "<div class='error_message'>";
echo "$error";
echo "</div>";
} 
?>
<center>
<form method="post" action="<?=$_SERVER['PHP_SELF']?>">
<p> Login into the game below or register <a href="register.php" title="register here">here</a>. You need to allow cookies and javascript, some firewalls
may block cookies. </p>
<p> Username: <input name="username" id="username" title="Username" value="" size="30" maxlength="16" /><br /></p>
<p> Password: <input name="password" id="password" type="password"  title="Password" value="" size="30" maxlength="24" /><br /></p>
<input type="submit" name="login" value="Login" title="Login into the Game">
</form>
</center>
<? 
include('includes/bottom.php'); 
?>

felgall · 08-28-2012, 08:15 AM

Change

Code:

<? 
include('includes/top.php');
include('includes/menu.php'); 
$error="";
if(isset($_SESSION['username'])){
header('location:default.php');
}

to

Code:

<? 
$error="";
if(isset($_SESSION['username'])){
header('location:default.php'); // this line needs to come
}
include('includes/top.php'); // before this line
include('includes/menu.php');

tangoforce · 08-28-2012, 11:09 AM

Please see the link in my signature about headers already sent.

The short version of the long story is:
Headers are sent BEFORE any html / text output. Therefore if you send text / html BEFORE a header, your header can not be sent.

In your top.php you have a lot of html output - you then come back out of it into login.php and try to send a header! This will not work.

For more information, please see the headers link in my signature.

connormcwood · 08-28-2012, 08:43 PM

Quote:

Originally Posted by felgall

Change

Code:

<? 
include('includes/top.php');
include('includes/menu.php'); 
$error="";
if(isset($_SESSION['username'])){
header('location:default.php');
}

to

Code:

<? 
$error="";
if(isset($_SESSION['username'])){
header('location:default.php'); // this line needs to come
}
include('includes/top.php'); // before this line
include('includes/menu.php');

I've done this and the error is still there:/.

Code:

<? 
$error="";
if(isset($_SESSION['username'])){
header('location:default.php');
}
include('includes/top.php');
include('includes/menu.php'); 

if(isset($_POST['login'])) {
include('includes/connect.php');
$username = $_POST['username'];
$password = md5($_POST['password']);
$query = "select * from users where username='$username' and password='$password'";
$result = mysql_query($query);
if (mysql_num_rows($result) != 1) {
$error = "Your username or password was Incorrect.";
} else {
    $_SESSION['username'] = $_POST['username'];
	header('Location: loggedin.php');
} } 
?>
<div id="rightbox">
<H2>Login</H2>
<? 
if(!$error == ""){
echo "<div class='error_message'>";
echo "$error";
echo "</div>";
} 
?>
<center>
<form method="post" action="<?=$_SERVER['PHP_SELF']?>">
<p> Login into the game below or register <a href="register.php" title="register here">here</a>. You need to allow cookies and javascript, some firewalls
may block cookies. </p>
<p> Username: <input name="username" id="username" title="Username" value="" size="30" maxlength="16" /><br /></p>
<p> Password: <input name="password" id="password" type="password"  title="Password" value="" size="30" maxlength="24" /><br /></p>
<input type="submit" name="login" value="Login" title="Login into the Game">
</form>
</center>
<? 
include('includes/bottom.php'); 
?>

tangoforce · 08-28-2012, 08:53 PM

session_start() before
if(isset($_SESSION['username'])){

Line 18 felgall, is this:

PHP Code:


			
} else {
    $_SESSION['username'] = $_POST['username'];
    header('Location: loggedin.php');

(The bit that comes after the html)