Headers warning

Question

Possible Duplicates:
Warning: Cannot modify header information - headers already sent by
what is output buffering?

I recently bought a hosting plan from Bluehost and moved my website here. Before, my website was working, and I haven't recieved any errors, but now, when I try to login I recieve this error:

Warning: Cannot modify header information - headers already sent by (output started at /home/rugbyspi/public_html/inc/offline_header.php:15) in /home/rugbyspi/public_html/index.php on line 84

The problem is the header function. I think I can't use this function in middle of the code, but on my other host I can do this. Any idea how to fix this problem?

<?php
session_start();
if (isset($_SESSION['username'])) {
   include_once('inc/homepage_header.php');
   include_once('lib/stats_func.php');
   include_once('lib/user_time_func.php');
   update_last_active($username);
?>

<div id="right_menu">
   <?php include_once('inc/sidebar_statistics.php'); ?>
   <br/>
   <?php include_once('inc/sidebar_follow.php'); ?>
</div>

<div id="content">
   <div class="text">
      <br/>
      <h2 class="hr"><?php echo $lang['ann']; ?></h2>
      <?php
      if(!isset($_REQUEST["start"])) {
         $start = 0;
      }
      else {
         $start = $_REQUEST["start"];
      }
      $query = mysql_query ("SELECT * from news where lang='$language'")
      or die ("Couldn't connect to the do database.");
      $d=0;
      $f=0;
      $g=1;
      $query = mysql_query ("SELECT * from news where lang='$language' order by id DESC Limit $start, 7") or die ("Couldn't connect to the do database.");
      while($news = mysql_fetch_array($query)) {
         ?>
         <h3 class="hr"><font size=1><?php echo $news['tsubmit']; ?></font>&nbsp;        &nbsp;<?php echo $news['title']; ?></h3>
         <?php
         echo $news['body'];
      }
      echo "<br/><br/><br/>";
      echo $lang['pages'] . ': ';
      while($order = mysql_fetch_array($query)) {
         if($f%7==0) {
            echo "<a href='index.php?start=$d'>$g</a>";
            $g++;
         }
         $d++;
         $f++;
      }
      ?>
   </div>
</div>

<?php
   include_once('inc/footer.php');
}
else {
   include_once('inc/offline_header.php');
   include_once('lib/stats_func.php');
?>

<div id="right_menu">
   <?php include_once('inc/sidebar_statistics.php'); ?>
   <br/>
   <?php include_once('inc/sidebar_follow.php'); ?>
</div>

<div id="content">
   <div class="text">
      <br/>
      <?php echo $lang['welcome']; ?>
      <br/><br/>
      <?php
      if (isset($_POST['submit'])) {
         $username = $_POST ['username'];
         $password = $_POST ['password'];
         $username = strip_tags ($username);   
         $password = md5 ($password);
         mysql_real_escape_string($username);
         $query = mysql_query ("SELECT id FROM users WHERE username='$username' AND password='$password'")
         or die ("Couldn't connect to the do database.") ;
         $result = mysql_fetch_array($query);
         if($result) {
            $_SESSION['username'] = $username;
            header('Location: index.php');
            if (!empty($_SERVER['HTTP_CLIENT_IP'])) {
               $ip=$_SERVER['HTTP_CLIENT_IP'];
            }
            elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
               $ip=$_SERVER['HTTP_X_FORWARDED_FOR'];
            }
            else {
               $ip=$_SERVER['REMOTE_ADDR'];
            }
            $time = time();
            mysql_query ("INSERT into logins (userid, time, ip)
            VALUES ('$result[id]', '$time', '$ip')")
            or die ("Couldn't connect to the database.");
         }
         else {
            echo $lang['login_error'];
         }
         echo '<br/><br/>';         
      }
      ?>
      <h2 class="hr"><?php echo $lang['about']; ?></h2>
      <?php echo $lang['intro']; ?>
   </div>
</div>

<?php
}
   include_once('inc/footer.php');
?> 

Answer 1

You must have some echoed text before you've started the session. Try removing any of the output before session_start(), or move that function to offline_header.php

Answer 2

It would be great if You provided a code from the line 15 an before from the error generating file. Anyway this error is caused by output done before session_start() or other header() function is called.

It doesn't matter whether it was Your output (like echo, print, etc) it also could be an output from error message (Notice, Warning) that could be turned off at previous hosting but now they appear before You call some header function...

You should check Your code on the line 15 and also all the code before whether it is generating some error or there is direct output...

Hope it helps.

Answer 3

As the error indicates, you cannot modify header information (which is what the header function does) once the header has already been sent. The headers get sent the first time you output text.

Before line 84 you have various places where text is output (for example lines 61, 63 and 65), and there could be more opportunities in the file which you include. This means that you cannot use the header function before theses lines, or possibly before any of the include calls in that else branch.

You should restructure your code to put

if (isset($_POST['submit'])) {...

as the first thing in the else branch, and don't output any html or other text until you know if the query succeeded, so that you know if you want to redirect to the index page.