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

zzz · 05-24-2009, 06:55 AM

hi,
can anybody help me i this regards.
problem is as follows

i have a form .
here i am getting a value through a file.
based on the value i decide the header.but before that i pass a meta data also.

<html>
<meta http-equiv="refresh" content="2;url=http://localhost/cba.php" />
<?php
$handle=fopen('c:/aaa.txt','r');
$a=fgets($handle);
fclose($handle);
if($a!=0)
header( 'refresh: 5; url=http://localhost/abc.php' );
else
header( 'refresh: 5; url=http://localhost/cba.php' );
?>
</html>

so here once i do this a warning will come up saying
"Warning: Cannot modify header information - headers already sent by (output started at C:\Program Files\Apache Group\Apache2\htdocs\abc.php:7) in C:\Program Files\Apache Group\Apache2\htdocs\abc.php on line 462
"

so can anyone give me solution for this.pls

jthayne · 05-29-2009, 12:46 PM

Sorry about the delayed response. I have been gone for a little while, but I am back now.

When using the header() function in PHP, there can be nothing output to the screen before the function is called. Any HTML is considered output to the screen. What you need to do is move your PHP code to before the HTML as follows:

PHP Code:


			
<?php
$handle=fopen('c:/aaa.txt','r');
$a=fgets($handle);
fclose($handle);
if($a!=0)
header( 'refresh: 5; url=http://localhost/abc.php' );
else
header( 'refresh: 5; url=http://localhost/cba.php' );
?>
<html>
<meta http-equiv="refresh" content="2;url=http://localhost/cba.php" />
</html>

Viola! No more error.

markei · 08-26-2009, 12:19 AM

Viola? Why not Bass Fiddle?

kaly · 11-02-2009, 03:44 AM

hi,
i m getting the same "Cannot modify header information - headers already sent in .. " error. There's no white space b4 or after php tags. Here is my code-

<? ob_start(); ?>
<?php
session_start();
if(isset($_POST['login']))
{
if(!$fh = fopen('pwd.dat','w')) {
do_error_exit('Error opening data file. <br />Please contact the system administrator. <br />Sorry for the inconvenience.');
}

$username1[0]= 'kaly';
$username1[1]= crypt('mypassword','rl');

$user_pass_string= implode('=',$username1);
fwrite($fh,"$user_pass_string\n");

flock($fh);
flush($fh);
fclose($fh);

$username = $_POST['username'];
$password = $_POST['pswd'];

$tempwd = crypt($password,'rl');

$fh = fopen('pwd.dat','r');

for($line = fgets($fh); !feof($fh) ; $line = fgets($fh))
{
$line = trim($line);
$userData = explode("=",$line);
if ($userData[0] == $username)
$pass = $userData[1];

}
fclose($fh);
if (crypt($password, $pass) == $pass){
$_SESSION['phplogin'] = true;
header('Location: index.php');
exit;
} else {
?>
<script type="text/javascript">

</script>
<?php
}
}
?><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title> PHP Login </title>
</head>
<body>
<center>
Username:<br>
Password:<br>
<form method="post" action="">
<input type="username" name="username">
<input type="password" name="pswd">
<input type="submit" name="login" value="Login">
</form>
</center>
</body>
</html>
<? ob_flush(); ?>

sac0o01 · 11-02-2009, 01:23 PM

I would say Short Tags are not enabled on your host. You can change it in your php.ini file but it is easiest to fix the code.

Change:

PHP Code:


			
<? ob_start(); ?>

To:

PHP Code:


			
<?php ob_start(); ?>

Remember to change the line at the bottom as well.

jthayne · 11-04-2009, 10:11 AM

Actually what needs to happen, is you need to move

PHP Code:


			
<? ob_start(); ?>

to just before you actually have output you are buffering as this function opens the output buffer which is where your problem lies.

My recommendation is to move it just before this line:

HTML Code:

<script type="text/javascript">

05-24-2009, 06:55 AM	#1
zzz New Member Join Date: Jan 2009 Webmaster Discussions: 5 Rep Power: 11	Warning: Cannot modify header information - headers already sent by (output started a hi, can anybody help me i this regards. problem is as follows i have a form . here i am getting a value through a file. based on the value i decide the header.but before that i pass a meta data also. <html> <meta http-equiv="refresh" content="2;url=http://localhost/cba.php" /> <?php $handle=fopen('c:/aaa.txt','r'); $a=fgets($handle); fclose($handle); if($a!=0) header( 'refresh: 5; url=http://localhost/abc.php' ); else header( 'refresh: 5; url=http://localhost/cba.php' ); ?> </html> so here once i do this a warning will come up saying "Warning: Cannot modify header information - headers already sent by (output started at C:\Program Files\Apache Group\Apache2\htdocs\abc.php:7) in C:\Program Files\Apache Group\Apache2\htdocs\abc.php on line 462 " so can anyone give me solution for this.pls

05-29-2009, 12:46 PM	#2
jthayne Join Date: Aug 2008 Location: Texas Webmaster Discussions: 501 Rep Power: 21	Re: Warning: Cannot modify header information - headers already sent by (output start Sorry about the delayed response. I have been gone for a little while, but I am back now. When using the header() function in PHP, there can be nothing output to the screen before the function is called. Any HTML is considered output to the screen. What you need to do is move your PHP code to before the HTML as follows: PHP Code: `<?php $handle=fopen('c:/aaa.txt','r'); $a=fgets($handle); fclose($handle); if($a!=0) header( 'refresh: 5; url=http://localhost/abc.php' ); else header( 'refresh: 5; url=http://localhost/cba.php' ); ?> <html> <meta http-equiv="refresh" content="2;url=http://localhost/cba.php" /> </html>` Viola! No more error. __________________ Be sure to click the reputation icon to give rep to the person who helped you. For web design/development services, check Silentium Designs. Last edited by jthayne; 05-29-2009 at 12:53 PM.

08-26-2009, 12:19 AM	#3
markei New Member Join Date: Mar 2009 Location: Westminster, MD Webmaster Discussions: 19 Rep Power: 10	Re: Warning: Cannot modify header information - headers already sent by (output start Viola? Why not Bass Fiddle?

11-02-2009, 03:44 AM	#4
kaly New Member Join Date: Nov 2009 Webmaster Discussions: 1 Rep Power: 6	Re: Warning: Cannot modify header information - headers already sent by (output start hi, i m getting the same "Cannot modify header information - headers already sent in .. " error. There's no white space b4 or after php tags. Here is my code- <? ob_start(); ?> <?php session_start(); if(isset($_POST['login'])) { if(!$fh = fopen('pwd.dat','w')) { do_error_exit('Error opening data file. <br />Please contact the system administrator. <br />Sorry for the inconvenience.'); } $username1[0]= 'kaly'; $username1[1]= crypt('mypassword','rl'); $user_pass_string= implode('=',$username1); fwrite($fh,"$user_pass_string\n"); flock($fh); flush($fh); fclose($fh); $username = $_POST['username']; $password = $_POST['pswd']; $tempwd = crypt($password,'rl'); $fh = fopen('pwd.dat','r'); for($line = fgets($fh); !feof($fh) ; $line = fgets($fh)) { $line = trim($line); $userData = explode("=",$line); if ($userData[0] == $username) $pass = $userData[1]; } fclose($fh); if (crypt($password, $pass) == $pass){ $_SESSION['phplogin'] = true; header('Location: index.php'); exit; } else { ?> <script type="text/javascript"> <!-- alert('Wrong Password, Please Try Again') //--> </script> <?php } } ?><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <head> <title> PHP Login </title> </head> <body> <center> Username:<br> Password:<br> <form method="post" action=""> <input type="username" name="username"> <input type="password" name="pswd"> <input type="submit" name="login" value="Login"> </form> </center> </body> </html> <? ob_flush(); ?>

11-02-2009, 01:23 PM	#5
sac0o01 New Member Join Date: Nov 2009 Location: USA Webmaster Discussions: 1 Rep Power: 6	Re: Warning: Cannot modify header information - headers already sent by (output start I would say Short Tags are not enabled on your host. You can change it in your php.ini file but it is easiest to fix the code. Change: PHP Code: `<? ob_start(); ?>` To: PHP Code: `<?php ob_start(); ?>` Remember to change the line at the bottom as well.

11-04-2009, 10:11 AM	#6
jthayne Join Date: Aug 2008 Location: Texas Webmaster Discussions: 501 Rep Power: 21	Re: Warning: Cannot modify header information - headers already sent by (output start Actually what needs to happen, is you need to move PHP Code: `<? ob_start(); ?>` to just before you actually have output you are buffering as this function opens the output buffer which is where your problem lies. My recommendation is to move it just before this line: HTML Code: <script type="text/javascript"> __________________ Be sure to click the reputation icon to give rep to the person who helped you. For web design/development services, check Silentium Designs.

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