(PHP 4, PHP 5)
exit — Output a message and terminate the current script
$status
  ] )$status
   )Terminates execution of the script. Shutdown functions and object destructors will always be executed even if exit is called.
   exit is a language construct and it can be called
   without parentheses if no status is passed.
  
status
       If status is a string, this function prints the
       status just before exiting.
      
       If status is an integer, that
       value will be used as the exit status and not printed. Exit statuses should be in
       the range 0 to 254, the exit status 255 is reserved by PHP and shall
       not be used. The status 0 is used to terminate the program
       successfully.
      
Note: PHP >= 4.2.0 does NOT print the
statusif it is an integer.
No value is returned.
Example #1 exit example
<?php
$filename = '/path/to/data-file';
$file = fopen($filename, 'r')
    or exit("unable to open file ($filename)");
?>
Example #2 exit status example
<?php
//exit program normally
exit;
exit();
exit(0);
//exit with an error code
exit(1);
exit(0376); //octal
?>
Example #3 Shutdown functions and destructors run regardless
<?php
class Foo
{
    public function __destruct()
    {
        echo 'Destruct: ' . __METHOD__ . '()' . PHP_EOL;
    }
}
function shutdown()
{
    echo 'Shutdown: ' . __FUNCTION__ . '()' . PHP_EOL;
}
$foo = new Foo();
register_shutdown_function('shutdown');
exit();
echo 'This will not be output.';
?>
The above example will output:
Shutdown: shutdown() Destruct: Foo::__destruct()
Note: Because this is a language construct and not a function, it cannot be called using variable functions.
Note:
This language construct is equivalent to die().