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POWarning: Cannot modify header information - headers already sent by
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  1. POWarning: Cannot modify header information - headers already sent by
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    copied!<blockquote> <p><strong>Possible Duplicate:</strong><br> <a href="https://stackoverflow.com/questions/1912029/warning-cannot-modify-header-information-headers-already-sent-by-error">&ldquo;Warning: Cannot modify header information - headers already sent by&rdquo; error</a> </p> </blockquote> <p>Hi All, </p> <p>I keep having a warning message appear when I try login. Can you help me rectify the problem.</p> <pre><code>Warning: Cannot modify header information - headers already sent by (output started at /path/to/login.php:15) in /path/to/login.php on line 231 </code></pre> <p>here's the php code before the html: </p> <pre><code>&lt;?php //allow sessions to be passed so we can see if the user is logged in session_start(); //connect to the database so we can check, edit, or insert data to our users table $con = mysql_connect('XXXXXXXXXXXXXXX', 'XXXXXXXXXXXX', 'XXXXXXXXXX') or die(mysql_error()); $db = mysql_select_db('XXXXXXXXXXXXXXXXX', $con) or die(mysql_error()); //include out functions file giving us access to the protect() function made earlier include "functions.php"; ?&gt; </code></pre> <p>Here is the functions.php file: </p> <pre><code>&lt;?php function protect($string){ $string = trim(strip_tags(addslashes($string))); return $string; } ?&gt; </code></pre> <p>and finally here is the PHP inside the HTML:</p> <pre><code>&lt;?php //If the user has submitted the form if($_POST['submit']){ //protect the posted value then store them to variables $username = protect($_POST['username']); $password = protect($_POST['password']); //Check if the username or password boxes were not filled in if(!$username || !$password){ //if not display an error message echo "&lt;center&gt;You need to fill in a &lt;b&gt;Username&lt;/b&gt; and a &lt;b&gt;Password&lt;/b&gt;!&lt;/center&gt;"; }else{ //if the were continue checking //select all rows from the table where the username matches the one entered by the user $res = mysql_query("SELECT * FROM `users` WHERE `username` = '".$username."'"); $num = mysql_num_rows($res); //check if there was not a match if($num == 0){ //if not display an error message echo "&lt;center&gt;The &lt;b&gt;Username&lt;/b&gt; you supplied does not exist!&lt;/center&gt;"; }else{ //if there was a match continue checking //select all rows where the username and password match the ones submitted by the user $res = mysql_query("SELECT * FROM `users` WHERE `username` = '".$username."' AND `password` = '".$password."'"); $num = mysql_num_rows($res); //check if there was not a match if($num == 0){ //if not display error message echo "&lt;center&gt;The &lt;b&gt;Password&lt;/b&gt; you supplied does not match the one for that username!&lt;/center&gt;"; }else{ //if there was continue checking //split all fields fom the correct row into an associative array $row = mysql_fetch_assoc($res); //check to see if the user has not activated their account yet if($row['active'] != 1){ //if not display error message echo "&lt;center&gt;You have not yet &lt;b&gt;Activated&lt;/b&gt; your account!&lt;/center&gt;"; }else{ //if they have log them in //set the login session storing there id - we use this to see if they are logged in or not $_SESSION['uid'] = $row['id']; //show message echo "&lt;center&gt;You have successfully logged in!&lt;/center&gt;"; //update the online field to 50 seconds into the future $time = date('U')+50; mysql_query("UPDATE `users` SET `online` = '".$time."' WHERE `id` = '".$_SESSION['uid']."'"); //redirect them to the usersonline page header('Location: usersOnline.php'); } } } } } ?&gt; </code></pre> <p>The main issue arises when I try redirect them to my usersOnline.php page.</p> <pre><code>//redirect them to the usersonline page header('Location: usersOnline.php'); </code></pre> <p>I have minimised all white space, but still have problems. Where the error informs me, line 15 is my meta id's (Description &amp; Keywords - SEO). Does this pose problems in PHP?</p> <p>Any help given is much appreciated as I am relatively new with PHP. </p> <p>Thanks, Darren</p>
 

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