How to Send HTTP Response Code in PHP

In PHP, you can send HTTP response codes to communicate the status of a request to the client. This is essential for proper web communication and helps browsers, APIs, and other clients understand how to handle the response.

Using http_response_code() Function

The http_response_code() function is the simplest method to set HTTP response codes in PHP 5.4+:

<?php
   // Set successful response
   http_response_code(200);
   
   // Set not found response
   http_response_code(404);
   
   // Set server error response
   http_response_code(500);
?>

This function must be called before any output is sent to the client. You can also retrieve the current response code by calling it without parameters:

<?php
   http_response_code(404);
   echo "Current response code: " . http_response_code(); // Outputs: 404
?>

Using header() Function

The header() function provides more control and works in all PHP versions:

<?php
   // Method 1: Full status line
   header("HTTP/1.1 404 Not Found");
   
   // Method 2: Using the third parameter
   header("Location: /login", true, 302);
   
   // Method 3: Setting just status
   header("Status: 503 Service Unavailable");
?>

The third parameter in header() allows you to set the response code directly, which is useful when redirecting or setting other headers.

Common Response Codes

Practical Example

Here's a practical example of using response codes in a simple router:

<?php
   $page = $_GET['page'] ?? 'home';
   
   switch($page) {
       case 'home':
           http_response_code(200);
           echo "Welcome to homepage";
           break;
       case 'admin':
           http_response_code(403);
           echo "Access forbidden";
           break;
       default:
           http_response_code(404);
           echo "Page not found";
   }
?>

Key Points

• Response codes must be set before any output is sent

• Use http_response_code() for PHP 5.4+ (recommended)

• Use header() for older PHP versions or more control

• Always choose appropriate codes based on the actual response status

Conclusion

Setting proper HTTP response codes is crucial for web communication. Use http_response_code() for simplicity or header() for more control, ensuring codes are set before any output is sent to the client.