C#面试问题2

32. What is polymorphism

多态性: There is one list, but it's elements can take many forms.

the derived types can bu used in place of the base type.

What mechanisms in C# allow us to use polymorphism?

interfaces, abstract classes, inheritance, virtual methods and generics.

33. What's the difference between a virtual method and abstract method

virtual method: In base class, it has an implementation, and it gives the inheriting classe an option to provide it's own implementation.

虚方法是实现多态的一个方法。

static methods cannot be virtual.

抽象方法：In base class, it does not have an implementation, and must be overriden.

They all can be applied to properties, indexers, and events.

What is method overriding?

It's providing a custom implementation of a virtual of abstract method in the child class.