PHP headers_sent() function
Definition and Usage
headers_sent() function checks if HTTP headers have been sent and where they were sent.
Returns true if headers have been sent, otherwise returns false.
Syntax
headers_sent(file,line)
| Parameter | Description |
|---|---|
| file,line | Optional. If set file and line Parameters, headers_sent() will store the name of the PHP source file and line number where the output started in the file and line variables. |
Tips and Comments
Comment:Cannot be used once the header block has been sent header() function to send other headers. Using this function can at least avoid error messages related to HTTP headers.
Comment:optional file and line The parameter is a new addition in PHP 4.3.
Example
Example 1
<?php
// If headers have not been sent, send one
if (!headers_sent())
{
header("Location: http://www.codew3c.com/");
exit;
}
?>
<html>
<body>
...
...
Example 2
Use optional file and line parameters:
<?php
// Pass $file and $line for future use
// Do not pre-assign them
if (!headers_sent($file, $line))
{
header("Location: http://www.codew3c.com/");
exit;
// Trigger an error here
}
else
{
echo "Headers sent in $file on line $line";
exit;
}
?>
<html>
<body>
...
...
