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This article introduces the knowledge of "how to use PHP callback function". Many people will encounter this dilemma in the operation of actual cases, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

PHP callback function

Callback function, a function structure that can achieve more functions with anonymous functions and variable functions.

What is a callback function?

The callback function in PHP actually means that when calling a function, instead of passing a standard variable as a parameter to the function, it passes another function as a parameter to the called function, and the callback function is the function that is used as a parameter.

It can be understood that the callback function is also a function we define, but it is not called directly, but requires another function to call.

Examples are as follows:

Output result:

In addition, PHP provides two functions, call_user_func () and call_user_func_array (), to support callback functions.

The difference between the two functions is that call_user_func_array () receives the parameters of the callback function as an array, while call_user_func () receives the parameters of the callback function as specific parameters.

Call_user_func_array ()

The call_user_func_array function can call the callback function and then use an array as an argument to the callback function. The syntax format is as follows:

Call_user_func_array ($callback, $param_arr)

In the grammatical format, $callback is the callback function that is called, and $param_arr is an indexed array. Here's an example to actually look at it:

Output result:

Call_user_func ()

The call_user_func function calls the first parameter as a callback function in the following syntax format:

Call_user_func ($callback [, $parameter,...])

Where $callback is the called callback function, and the remaining arguments are the parameters of the callback function, separated by ",". Here's an example to actually take a look at:

Output result:

Next, let's share with you an example of the combination of a variable function and a callback function:

Output result:

That's all for "how to use the PHP callback function". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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