## Example

`

     bool headers_sent ([ string &$file [, int &$line ]] )

`

## Description

Checks if or where headers have been sent. You can't add any more header lines using the header() function once the header block has already been sent. Using this function you can at least prevent getting HTTP header related error messages. Another option is to use Output Buffering.

## Return Values

headers_sent() will return FALSE if no HTTP headers have already been sent or TRUE otherwise.