Introduction and example usage of abstract method and abstract class abstract keyword of PHP

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PHP Abstract methods and Abstract Class abstract keywords

The abstract keyword is used to define abstract methods and classes.

Abstract method

An abstract method refers to a method without a method body, specifically without {} parentheses and its contents when the method is declared, but directly ending with a semicolon after the method name.

The abstract keyword is used to define abstract methods, syntax:

Abstract function function_name ()

Abstract class

As long as a method in a class is an abstract method, the class is defined as an abstract class. Abstract classes are also defined using the abstract keyword.

Abstract classes cannot produce instance objects, they are usually used as templates for overloading subclass methods, and all methods in inherited abstract classes are implemented. In fact, abstract classes are introduced to facilitate inheritance.

Example:

The copy code is as follows:

In this example, the parent class defines the abstract method and the implementation of the method, but the actual content is defined in the subclass.

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