PHP标头（位置）错误

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;        
}

Answer 1

If headers are already sent the JS method should work.

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