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Use header() with exit: avoid subsequent code execution

M66 2025-05-28

In PHP programming, header() and exit() are two very common functions. They are often used to control HTTP responses and end the execution of the program, especially when pages are redirected. Understanding how to correctly match these two functions can effectively prevent the PHP program from continuing to execute unnecessary code after jumping.

Header() function introduction

The header() function is used to send raw HTTP header information. Through this function, we can control page redirection, cache control, content type, etc. One of the most common uses is redirection, i.e. through the Location header, instructs the browser to jump to another page.

example:

 header('Location: https://m66.net/some-page.php');
exit;

The above code will redirect the user to the https://m66.net/some-page.php page, and use exit() to end the execution of the current script, ensuring that the subsequent code will not continue to be executed after the redirect.

exit() function introduction

The exit() function (can also be replaced by die() ) is used to terminate the execution of the current script. If exit() is not called after executing header() , subsequent code will continue to be executed, which may lead to unwanted side effects, such as unnecessary database operations or HTML output.

How to avoid the code execution after jumping?

When we use header() to implement page redirection, the program will continue to execute subsequent code until the script ends or encounter exit() or die() . If you do not use exit() , subsequent PHP code will continue to be executed even if the page jump has occurred.

Question example:

 header('Location: https://m66.net/some-page.php');
// The subsequent code will continue to be executed，Even if it has already jumped
echo "This is some debug information.";

In the example above, even though the browser has received a redirected response, PHP will still execute an echo statement to output the content to the browser. This is not only a waste of performance, but can also lead to unnecessary errors or output information.

The correct way to do it:

To avoid this, use exit() to terminate script execution. This ensures that after performing a jump operation, the PHP script no longer executes any code.

 header('Location: https://m66.net/some-page.php');
exit;  // Terminate script execution

In this way, the page will be redirected to the specified address, and subsequent code will not be executed, thus avoiding unnecessary output.

When to use header() and exit()?

  1. Page jump : If you want to implement page redirection in PHP, you usually use header('Location: URL') to jump, and then use exit() to avoid the code execution.

  2. Security : In some cases, you may want to jump to the login page, error page, etc. under certain conditions. In this case, header() and exit() are very important combinations.

  3. Performance optimization : When jumps are required, make sure that the program does not perform any additional processing, reducing unnecessary overhead and resource waste.

Summarize

The header() function is a very useful tool that can help developers to redirect pages. However, if not used with exit() , the code may continue to execute, resulting in unnecessary output and problems. By combining header() and exit() , you can ensure the smoothness and safety of the code, and avoid continuing to execute subsequent code logic after jumping.

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