The difference between abstract and virtual in C #

From:https://www.cnblogs.com/zyj649261718/p/6256327.html

In C #, abstract and virtual are easier to confuse, are related to inheritance, and involve the use of override. The difference between the two is discussed below:

First, virtual method (virtual method)

The virtual keyword is used to decorate a method in a base class. There are two things you can do with virtual:

Scenario 1: The virtual method is defined in the base class, but the virtual method is not overridden in the derived class. In a call to a derived class instance, the virtual method uses the method defined by the base class.

Scenario 2: The virtual method is defined in the base class and then overridden in a derived class by using override. In a call to a derived class instance, the virtual method uses the derived overridden method.

Ii. Abstract Method (Abstraction method)

The abstract keyword can only be used to decorate a method in an abstraction class , and there is no specific implementation. An implementation of an abstract method must be implemented in a derived class by using the override keyword.

The most essential difference between an interface and an abstract class: an abstract class is an incomplete class, an abstraction of an object, and an interface is a behavior specification.

Third, the key words

static: When a method is declared as static, the method is a static method, and the compiler retains the implementation of the method at compile time. That is, the method belongs to a class, but does not belong to any member, regardless of whether the instance of the class exists or not. Just like the entry function static void Main, because it is a static function, it can be called directly.

Virtua: When a method is declared as virtual, it is a dummy method until you use ClassName variable = new ClassName (); Before declaring an instance of a class, it does not exist in the real memory space. This keyword is very common in class inheritance and is used to provide polymorphism support for class methods.

Overrride: Indicates that overriding this class is inherited from the shape class
Virtual,abstract is telling other classes that want to inherit from him that you can rewrite my method or property, otherwise it is not allowed.


Abstract: The abstraction method declaration is used as a method that must be overridden by a derived class, which is used to inherit, and can be seen as a virtual method without implementing a body, and if the class contains an abstract method, the class must be defined as an abstract class, whether or not it contains other general methods, and the abstract class cannot have entities.

The difference between abstract and virtual in C #