PHP Header (Location) errors

Question

Whenever i open the page i receive following errors:

[04-Jul-2012 17:10:45] PHP Warning: Cannot modify header information - headers already sent by (output started at /home/test/public_html/admin/header.php:39) in /home/test/public_html/admin/edAgent.php on line 80

[04-Jul-2012 17:10:55] PHP Warning: Cannot modify header information - headers already sent by (output started at /home/test/public_html/admin/header.php:39) in /home/test/public_html/admin/edAgent.php on line 80

Pieces of code including headers:

Encoding header:

header('Content-Type: text/html; charset=utf-8');

Login redirect header:

if(!isset($_SESSION["login"])OR $_SESSION["login"]!=1){        
    header('Location: login.php');
    exit;     
    }

Checks if logged user has privileges to edit:

if($level!='4') {
    header('Location: acd.php?msg=1');
    exit;
}

Checks if ID exists:

if ($nUsers==0) {    
    header('Location: acd.php?msg=2');
    exit;    
}

Checks if information is editable:

if($access != '4') {        
    header('Location: acd.php?msg=1');
    exit;        
}

Take a look at line 39 of /home/test/public_html/admin/header.php - the error message gives you a really big clue there — Paul Dixon, Jul 05 '12 at 09:58
possible duplicate of [Headers already sent by PHP](http://stackoverflow.com/questions/8028957/headers-already-sent-by-php) — Paul Dixon, Jul 05 '12 at 10:00
Line 39 will just be the first line of code that outputs anything to the client. It in itself will not be or cause an error. The writing to screen will cause the headers to be sent. — Joe Bowman, Jul 05 '12 at 10:00
@GeoPhoenix I use exit to stop executing code after redirect. — John, Jul 05 '12 at 10:02

score 2 · Answer 1 · answered Jul 05 '12 at 09:59

2

If you output ANYTHING to screen then, headers will write. So if you intend to use header() in your code, you must either do this before outputing anything, or right at the begining turn on output buffering using ob_start().

answered Jul 05 '12 at 09:59

Joe Bowman

536
2
8

score 1 · Accepted Answer · answered Jul 05 '12 at 11:21

1

If headers are already sent the JS method should work.

print '<script type="text/javascript">window.top.location.href = "'. $myurl .'";</script>';

answered Jul 05 '12 at 11:21

RassK

515
6
20

score 0 · Answer 3 · answered Jul 05 '12 at 10:09

0

add ob_start(); at the start of page and ob_end_flush(); and the end of the page. Try store header() in functions though you should not have any output code after the header().

Hope it helps

answered Jul 05 '12 at 10:09

JohannesAndersson

4,550
2
17
30

PHP Header (Location) errors

3 Answers3