PHP Forum

**GlyndwrBartlett** · 12-07-2005, 04:05 AM

I am getting the error "Cannot modify header information - headers already sent by..." you know the rest. I have searched and found a number of people asking the same question however I do not understand the responses.

1) White space in the code - how do I find the white space to remove it?
2) No HTML output - sorry how do I get round this?

The php file I am running is:

PHP Code:


			
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html><head><title>Web Template by Glyndwr D. Bartlett</title>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
<meta content="CD Copyright © 2005 Glyndwr D. Bartlett" name="description">
<meta content="Glyndwr D. Bartlett" name="author"></head>
<?php
//Quote variable to make safe
function quote_smart($value)
{
//Strip slashes
if (get_magic_quotes_gpc()) {
$value = stripslashes($value);
}
//Quote if not integer
if (!is_numeric($value)) {
$value = "'" . mysql_real_escape_string($value) . "'";
}
return $value;
}
//Connect
$link=mysql_connect("127.0.0.1","root")
OR die(mysql_error());
$db=mysql_select_db("db1",$link);
//Check validity of UserName and Password
if(isset($_POST['LogIn_x'])) {
$query = sprintf("SELECT * FROM tbl_user WHERE User_Name=%s AND Password=md5(%s)",
quote_smart($_post['UserName']), quote_smart($_post['PassWord']));
$result = mysql_query($query);
$affected = mysql_num_rows($result);
if ($affected != 1) {
session_unset();
echo "<font face='Verdana' size='2' color=red>Wrong Login. Use your correct UserID and Password and try again. <br>";
echo "<center> <input type='button' value='Retry' onClick='history.go(-1)'></center>";
exit();
}
}
//If Reset was selected we redirect to the homepage.
?>
<?php
if(isset($_POST['Reset_x']))
{
header ("Location: index.php");
exit();
}
?>
</html>

The error comes from the fifth last line header "("Location: index.php");".
The page I am going to is:

PHP Code:


			
<?
if(file_get_contents("lang.tmp")=="")
{
header("Location: splash.php"); 
exit();
}
?>
<html>
<head>
<meta name="author" content="Glyndwr D. Bartlett">
<title>Kortge Cutlers</title>
<frameset rows="140,*" marginwidth="0" marginheight="0" frameborder="0" border="0" borderwidth="0">
<frame name="head" src="head.php" scrolling=no>
<frameset cols="225,*,225" marginwidth="0" marginheight="0" frameborder="0" border="0" borderwidth="0">
<frame name="navi" src="navi.php" scrolling=auto>
<frame name="content" src="start.php" marginwidth=20>
<frame name="login" src="login.php" marginwidth=20 scrolling=no>
</frameset>
</frameset>
</head>
<body bgcolor=#ffffff>
</body>
</html>

Your help is greatly appreciated.

Regards,

Glyn

**chrishirst** · 12-07-2005, 04:39 AM

you can't send out redirect headers once output has been sent

**reli4nt** · 12-08-2005, 08:52 AM

Code:

<?php
if(isset($_POST['Reset_x']))
{
header ("Location: index.php");
exit();
}
?>

make sure that this the first thing on the page with not so much as a white space before the opening php tag.

The <!doctype html... is unneccessary if the visitor is getting redirected anyway.

the other option it to buffer the output so nothing will be sent til the header situation is resolved using ob_start() but I strongly recommend the first as the most practical and efficient.

**GlyndwrBartlett** · 12-08-2005, 11:51 PM

I was able to resolve this problem, with further investigation, by creating a ".htaccess" file and putting the following line in it " PHP_FLAG output_buffering on".

chrishirst: I do not know what you mean.

reli4nt: I will also try your suggestions and let you know if it works.

Regards,

Glyn

**chrishirst** · 12-09-2005, 03:16 AM

As in reli4nt's answer

You are sending the header after the page output has started (The doctype etc). Even sending a single space to the user agent is output and will cause the message to be shown.

Any code using header() must be executed first.

**GlyndwrBartlett** · 12-09-2005, 03:22 AM

Hi reli4nt,

As promised I have tested your solution to the problem. First I removed the file I created and ensured that I had the original problem. I then put your code in. I still had the original problem. I then replaced the file and it worked. So your code is not the resolution. The resolution is the ".htaccess" file containing the line " PHP_FLAG output_buffering on".

I hope this of help to others.

I now have another problem which I will make the subject of another Post.

Regards,

Glyn

**reli4nt** · 12-09-2005, 06:45 AM

Not every one has access to .htaccess.

Would you mind showing me what you code looked like after you tried my fix?

**GlyndwrBartlett** · 12-10-2005, 08:02 AM

Hi Reli4nt,

All too happy to help. I just added the lines you recomended and removed the equivalent lines.

Why is it that not every one has access to ".htaccess"? This may be important for me in the future if I move off my tablet PC.

PHP Code:


			
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html><head><title>Web Template by Glyndwr D. Bartlett</title>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
<meta content="CD Copyright © 2005 Glyndwr D. Bartlett" name="description">
<meta content="Glyndwr D. Bartlett" name="author"></head>
<?php
if(isset($_POST['Reset_x']))
{
header ("Location: index.php");
exit();
}
//Quote variable to make safe
function quote_smart($value)
{
//Strip slashes
if (get_magic_quotes_gpc()) {
$value = stripslashes($value);
}
//Quote if not integer
if (!is_numeric($value)) {
$value = "'" . mysql_real_escape_string($value) . "'";
}
return $value;
}
//Connect
$link=mysql_connect("127.0.0.1","root")
OR die(mysql_error());
$db=mysql_select_db("db1",$link);
//Check validity of UserName and Password
if(isset($_POST['LogIn_x'])) {
$query = sprintf("SELECT * FROM tbl_user WHERE User_Name=%s AND Password=md5(%s)",
quote_smart($_post['UserName']), quote_smart($_post['PassWord']));
$result = mysql_query($query);
$affected = mysql_num_rows($result);
if ($affected != 1) {
session_unset();
echo "<font face='Verdana' size='2' color=red>Wrong Login. Use your correct UserID and Password and try again. <br>";
echo "<center> <input type='button' value='Retry' onClick='history.go(-1)'></center>";
exit();
}
}
</html>

Regards,

Glyn

**chrishirst** · 12-10-2005, 02:07 PM

Actually the resolution would be to put the redirect part of the code before the doctype rather than change the buffering which could cause other problems.

**GlyndwrBartlett** · 12-12-2005, 03:23 AM

I will try that chrishirst and let you know the result.

Thanks,

Glyn

**GlyndwrBartlett** · 12-13-2005, 02:13 AM

Hi chrishirst,

That worked as well. Thanks mate.

Regards,

Glyn

P.s. I don't suppose any one knows how to get the page to load on it's own instead of in the frame it came from, as per my other post?

**execute** · 12-13-2005, 04:39 PM

You can also use your php code this way:

<?php
ob_start();
//your whole script
ob_end_flush();
?>
That will fix all header problems.

**execute** · 12-13-2005, 11:03 PM

BTW your .htaccess thing about PHP_FLAG output_buffering on

Doesn't seem to work well. I get blank pages, but when i use ob_start it works. I have never heard of PHP_FLAG output_buffering on but it sounds cool, but i wasnt able to get it to work.

**execute** · 12-17-2005, 02:07 PM

I dont get blank page i'm sorry i still get "cannot modify cookies" and errors like that, when i use PHP_FLAG output_buffering on
in my Htaccess
however if i type ob_start(); and ob_end_flush(); it works.

**reli4nt** · 12-17-2005, 03:29 PM

Just remember that header() session_start() etc. need to be used before any html is sent to the browser.

When i said to make sure it was the first thing on the page I meant the FIRST thing. This isnt html so you can run a dozen scripts before even the doctype is sent to the browser but once the doctype info or so much as a space occurs outside of the php tags or an echo occurs within then no header info can be sent.