headers_sent

Definition and usage

headers_sent() function checks whether the header has been sent/sent to where it is sent.

Example

Example 1

If no header is sent, send one:

 <?php
if ( ! headers_sent ( ) ) {
  header ( "Location: https://www.gitbox.net/" ) ;
  exit ;
}
?>

< html >
< body >

...
...

Example 2

Use optional file and line parameters:

 <?php
// Pass in $file and $line for subsequent use
// Don't assign them in advance
if ( ! headers_sent ( $file , $line ) )
  {
  header ( "Location: https://www.gitbox.net/" ) ;
  exit ;
  // Error triggered here
  }
else
  {
  echo "Headers sent in $file on line $line " ;
  exit ;
  }
?>

< html >
< body >

...
...

grammar

 headers_sent ( file , line )

Parameter value