Virtual method and Overwrite method

usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingSystem.Text;namespacenange_1{classA { Public voidF () {Console.WriteLine ("in the base class"); }    }    classb:a { Public voidF () {Console.WriteLine ("in the child class"); }    }    classProgram {Static voidMain (string[] args) {B OBJB=NewB (); A Obja=OBJB;   The //base class points to the derived class object obja.f (); //But the method of the base class is still called!        Console.ReadLine (); }    }}
Output Result:

UsingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingSystem.Text;namespacenange_1{classA {Virtual  Public voidF () {Console.WriteLine ("in the base class"); }    }    classb:a {Override  Public voidF () {Console.WriteLine ("in the child class"); }    } classProgram {Static voidMain (string[] args) {B OBJB=NewB (); A Obja=NewA (); OBJA.F (); the//base class calls its own method Obja= (A) objb;//add No (A) all the same! Base class reference points to derived class objectOBJA.F (); //Call the method of the derived class at this time! It's totally different from the top!            Objb.f ();        Console.ReadLine (); }           }}
/*important information about the virtual and override modifiers is as follows: overwriting and overwriting methods must have the same accessibility! Static and non-virtual methods cannot be replicated. Methods, properties, indexers, and another type of member event (all can be declared as virtual and override)*/
Summary: this and C + + inside the virtual function effect is the same! It's called Polymorphism! 

Virtual method and Overwrite method