(PHP 5 >= 5.4.0, PHP 7)
http_response_code — Get or Set the HTTP response code
Gets or sets the HTTP response status code.
response_code
       The optional response_code will set the response code.
      
   If response_code is provided, then the previous
   status code will be returned. If response_code is not
   provided, then the current status code will be returned. Both of these
   values will default to a 200 status code if used in a web
   server environment.
  
   FALSE will be returned if response_code is not
   provided and it is not invoked in a web server environment (such as from a
   CLI application). TRUE will be returned if
   response_code is provided and it is not invoked in a
   web server environment (but only when no previous response status has been
   set).
  
Example #1 Using http_response_code() in a web server environment
<?php
// Get the current response code and set a new one
var_dump(http_response_code(404));
// Get the new response code
var_dump(http_response_code());
?>
The above example will output:
int(200) int(404)
Example #2 Using http_response_code() in a CLI environment
<?php
// Get the current default response code
var_dump(http_response_code());
// Set a response code
var_dump(http_response_code(201));
// Get the new response code
var_dump(http_response_code());
?>
The above example will output:
bool(false) bool(true) int(201)