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This article introduces the knowledge of "how to use the spl_autoload_register () and _ _ autoload () functions in PHP". 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!

In daily development and use, the basic idea of our object-oriented programming is that we are usually accustomed to creating a separate PHP source file for each class, so that it is convenient for later maintenance and easy to reuse classes.

In PHP, we can realize the automatic loading of the class through the spl_autoload_register () and _ _ autoload () functions, which can save our programming time and effort. Then let's introduce these two functions separately.

_ _ autoload () function

To be exact, the _ _ autoload () function is a magic method. We introduce some commonly used magic methods in detail in "five minutes to show you the magic methods in PHP (detailed explanation of examples)". It is mentioned that it is called automatically, that is, functions need to be called under specific conditions early.

When we new a class, if the class cannot be found in the current source file, PHP automatically calls the _ _ autoload () function and passes the class name to the _ _ autoload () function. This is the specific condition for the _ _ autoload () function call. Its syntax format is as follows:

Function _ _ autoload ($class) {/ / method body}

One of the things we need to pay attention to is:

$class is the name of the class to load.

The _ _ autoload () function can only be defined once in the current source file.

To load a class file automatically using the _ _ autoload () function, the class file name needs to be the same as the class name, and only one class can be defined in another class file.

Next, let's take a look at the use of the _ _ autoload () function through an example, as follows:

Running the above code will automatically load the Demo.php file in the same directory. The code in Demo.php is as follows:

It is important to note that the _ _ autoload () function has been deprecated since PHP7.2.0 and can be replaced by the spl_autoload_register () function.

Spl_autoload_register () function

The spl_autoload_register () function can specify a function to replace the function of the _ _ autoload () function.

Spl_autoload_register ([$autoload_function [, $throw = true [, $prepend = false])

Among them, it should be noted that:

Autoload_function: to replace the function name of the _ _ autoload () function, it can also be an anonymous function. If no parameters are provided, the default implementation function spl_autoload () of autoload is automatically registered.

$throw: used to set whether the spl_autoload_register () function throws an exception when $autoload_function fails to register successfully

$prepend: if it is true, the spl_autoload_register () function adds the $autoload_function function to the beginning of the queue, otherwise to the end of the queue.

Next, let's take a look at the example, which is as follows:

In the above example, the spl_autoload_register () function is used to specify another function instead of the _ _ autoload () function.

That's all for "how to use the spl_autoload_register () and _ _ autoload () functions in PHP". 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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