Programming Forums - View Single Post - Warning: Cannot modify header information - headers already sent by (output started at

Sane · Jan 12th, 2008, 8:37 AM

The function, "header", can not be called if you've already made the script output text to the client.

For example:

 PHP Syntax (Toggle Plain Text) 
<?php
 
echo 'Hello World!'
header('Content-type: text/plain');
 
?>
<?php

echo 'Hello World!'
header('Content-type: text/plain');

?>

Will throw an error, because it tried to modify the header after all of the headers were sent to the client.

 PHP Syntax (Toggle Plain Text) 
<?php
 
header('Content-type: text/plain');
echo 'Hello World!'
 
?>
<?php

header('Content-type: text/plain');
echo 'Hello World!'

?>

This will work. Because the header is modified, and then output is sent.

Jan 12th, 2008, 8:37 AM	#2
Sane Programming Guru Join Date: Apr 2005 Posts: 1,799 Rep Power: 5	Re: Warning: Cannot modify header information - headers already sent by (output started at The function, "header", can not be called if you've already made the script output text to the client. For example: PHP Syntax (Toggle Plain Text) <?php echo 'Hello World!' header('Content-type: text/plain'); ?> <?php echo 'Hello World!' header('Content-type: text/plain'); ?> Will throw an error, because it tried to modify the header after all of the headers were sent to the client. PHP Syntax (Toggle Plain Text) <?php header('Content-type: text/plain'); echo 'Hello World!' ?> <?php header('Content-type: text/plain'); echo 'Hello World!' ?> This will work. Because the header is modified, and then output is sent.