How to check if Headers already been sent in PHP

Question

I think most of us know about the infamous \"Headers already sent\" error in PHP. Can I check someway if headers already have been sent?

It would be really handy to

Answer 1

PHP has a function headers_sent() which allows you to check if the headers are already sent out before you take any action. Here’s how you could use the function in your code:

if(headers_sent())
{ //if headers already sent out print some message.
echo "Please go to yahoo.com";
}
else{
//send the user automatically to test.php
header('Location: http://yahoo.com');
exit;
}