logo search
CSharp_Prog_Guide

Результат

CoOrds 1: x = 10, y = 20

Inheritance

Classes can inherit from another class. This is accomplished by putting a colon after the class name when declaring the class, and naming the class to inherit from—the base class—after the colon, as follows:

public class A

{

public A() { }

}

public class B : A

{

public B() { }

}

The new class—the derived class—then gains all the non-private data and behavior of the base class in addition to any other data or behaviors it defines for itself. The new class then has two effective types: the type of the new class and the type of the class it inherits.

In the example above, class B is effectively both B and A. When you access a B object, you can use the cast operation to convert it to an A object. The B object is not changed by the cast, but your view of the B object becomes restricted to A's data and behaviors. After casting a B to an A, that A can be cast back to a B. Not all instances of A can be cast to B—just those that are actually instances of B. If you access class B as a B type, you get both the class A and class B data and behaviors. The ability for an object to represent more than one type is called polymorphism.

Structs cannot inherit from other structs or classes. Both classes and structs can inherit from one or more interfaces.