C # Base Key understanding

The largest use place of the base is on the polymorphism of the polygon-relative development. (What is polymorphism, how to understand polymorphism)

Base can "finish" calling its base class constructor when creating an instance of a derived class or calling a method on a base class that has been overridden by another method

About base Call base class constructor (only one class constructor calls another class's constructor)

public Class A {public        a () {            Console.WriteLine ("Build a");        }    }    public class B:a {public        B (): Base ()        {            Console.WriteLine ("Build B");            }    }
Create an instance object of B, and get the result of both build a and build B.

Instantiate Class B

         Build//Further expand  Call the base class constructor's public  class BaseClass

{
int num;
Public BaseClass ()
{
Console.WriteLine ("In BaseClass ()");
}
public BaseClass (int i)
{
num = i;
Console.WriteLine ("In BaseClass (int {0})", num);
}
}
public class Derivedclass:baseclass
{
The constructor calls Baseclass.baseclass ()
Public DerivedClass ()
: Base ()
{
}
The constructor calls Baseclass.baseclass (int i)
Public derivedclass (int i)
: Base (i)
{
}
static void Main ()
{
DerivedClass dc = new DerivedClass ();
DerivedClass DC1 = new DerivedClass (1) ();
Console.ReadLine ();
}
}

A method that always calls a base class in a derived class (which is actually an override of a virtual method)

    public class Q {public        virtual void Hello () {            Console.WriteLine ("Hello");        }    }    public class W:q {public        override void Hello ()        {            base. Hello ();            Console.WriteLine ("World");        }    }
    Instantiate  class W
    Output  Hello World

　　

C # Base Key understanding