PHP magic function analysis: register_shutdown_function()

There are many magic functions in the PHP language, which provide developers with many convenient functions. One of the very important functions is register_shutdown_function().

register_shutdown_function() function is PHP's termination processing function. This function can register a callback function that will be executed after the PHP script is executed. This callback function will be executed whether it ends normally or abnormally (such as server crash, etc.). This is useful for managing servers and preventing script leaks.

Let’s take a look at the detailed usage of the register_shutdown_function() function.

Basic syntax

register_shutdown_function(callable $callback, mixed $parameter = null):void;

Parameter description

$callback: the callback that needs to be executed Function

$parameter: Will be passed as the parameter of the $callback function. If you need to add multiple parameters, you can use an array.

Instance analysis

The following is an example. When the PHP script is executed, the callback function will output a paragraph:

function my_shutdown_function() {

echo "脚本执行完毕!

";
}

register_shutdown_function('my_shutdown_function');

Multiple callback functions

When multiple callback functions are needed, multiple functions can be registered. PHP will execute these functions in the order they are registered.

function shutdown_function_1() {

echo "第一个回调函数!

";
}

function shutdown_function_2() {

echo "第二个回调函数!

";
}

register_shutdown_function('shutdown_function_1');
register_shutdown_function('shutdown_function_2');

end() function is equivalent to register_shutdown_function()

In the PHP7.2 version, PHP has added a new function end(), which has basically the same function as register_shutdown_function(). The difference is that the end() function only accepts a callback function as a parameter and does not support passing Parameters.

The following is an example of an end() function:

function my_shutdown_function() {

echo "脚本执行完毕!

";
}

end( 'my_shutdown_function');

Summary

register_shutdown_function() function is a very important magic function in PHP. It can execute the callback function after the PHP script is executed, whether it ends normally or abnormally. Normal completion will be executed. This function is very useful in terms of server administration and script security.

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