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This article mainly introduces what magic methods there are in php language. It is very detailed and has certain reference value. Friends who are interested must finish reading it.

Php magic methods include: "_ _ set ()", "_ _ get ()", "_ _ isset ()", "_ _ unset ()", "_ _ sleep ()", "_ _ wakeup ()", "_ _ call ()", "_ _ invoke ()", "_ _ set_state ()" and so on.

Operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

In object-oriented programming, PHP provides a series of magic methods, which provide a lot of convenience for programming, and play a very important role in PHP. Magic methods in PHP usually start with _ _ (two underscores) and do not need to be called explicitly but automatically under certain conditions.

The magic methods in PHP are shown in the following table:

The magic method automatically calls _ _ destruct () when it instantiates the class _ _ construct () class object automatically calls _ _ set () at the end of use, automatically calls _ _ get () when assigning values to undefined attributes, automatically calls _ _ isset () when it uses isset () or empty () function, automatically calls _ _ sleep () when using unset () to make Automatically call _ _ wakeup () when serializing with serialize _ _ wakeup () automatically call _ _ call () when using unserialize deserialization to call a method that does not exist call _ _ callStatic () automatically call _ _ toString () when calling a static method that does not exist automatically call _ _ invoke () when trying to call an object when a method is called automatically call _ _ set_state () when using var Called automatically when the _ export () function Accept an array parameter _ _ clone () automatically called when copying an object using clone _ _ debugInfo () when printing object information using var_dump ()

_ _ autoload ()

Try to load an undefined class

Example

Let's explain how to use these magic methods in the form of examples.

1. _ _ construct (), the constructor of the class

The constructor in php is the first method that is automatically called by the object after the object is created. There is a constructor in each class, and if it is not declared explicitly, there is a constructor with no parameters and empty content by default in the class.

1. The function of construction method.

Constructors are often used to perform useful initialization tasks, such as assigning initial values to member properties when creating an object.

2. the declaration format of the constructor in the class

Function _ _ constrct ([parameter list]) {method body / / is usually used to initialize the assignment of member attributes}

3. Things to pay attention to when declaring constructors in a class

1) only one constructor can be declared in the same class because PHP does not support constructor overloading.

2). The name of the constructor is _ _ construct () starting with two underscores.

Here is an example of it:

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