How to call base method from derived class instance in C#?

You can only call your base class's methods from the derived class (B) by doing:

base.print();

I don't think there is a way to do what you want to do, because it kind of breaks the point of polymorphism.

However, you can hide the print method in A by doing this in B:

new public void print() { Console.WriteLine("b"); }

This way, this code:

A a= new B();
a.print();

will call the print in A.

Thanks to everyone! Finally I realize this behavior need using reflection and delegate, like nocodename showing, here I find a similar method.

A a = new B();
var ptr = typeof(A).GetMethod("Print", new[] { typeof(_inputParameter) }).MethodHandle.GetFunctionPointer();
var baseGetItem = (Func<String, String>)Activator.CreateInstance(typeof(Func<String, String>), a, ptr);
String postedValue = baseGetItem(_parameter);

You can't call base print outside of a class B i.e. from Main method due to way how override works in c#. However if you want to have possibility to do that, you should consider to shadow print method in class B:

public class B:A
{
    public new void print() { Console.WriteLine("b"); }
}

With new keyword class shadows member from parent class, so your line of code will work:

A a= new B();
a.print(); //prints "a"

and

B b= new B();
b.print(); //prints "b"

The whole idea of override is that you will not call the base class's function. If you want to call A.print - use A object, if you want to call B.print use B object, and if you want an object that can use some of that and some of that - create it separately or use functions with different names, that might solve your problem.

I'm not sure what you are trying to accomplish here, but maybe you would like to read about Visitor Pattern

Good Luck!

You can simply call base class method from derived class by using "base" keywork:

see example,

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            B obj= new B();
            obj.print();
            Console.ReadKey();
        }
    }

    public class A
    {
        public virtual void print() { Console.WriteLine("a"); }
    }
    public class B : A
    {
        public override void print() 
        {
            base.print();
            Console.WriteLine("b"); 
        }
    }

}

hope you understand! Thank u

You cannot call the base method when you override it in the inherited. You can make the method in B to be new instead of override, but you lose the implementation.

public class A
{
    public virtual void Print() { Console.WriteLine("a"); }
}

public class B: A
{
    public new void Print() { Console.WriteLine("b"); }
}

This way when you call

static void Main(string[] args)
{
    A a = new B();
    a.Print(); // prints "a"
}

Otherwise, you can call base.Print() in the overridden method.

public class A
{
    public virtual void Print() { Console.WriteLine("a"); }
}

public class B: A
{
    public override void Print() 
    {
        base.Print();
        Console.WriteLine("b"); 
    }
}

It's easy enough to get around this. In the base class:

  protected void MethodToExtend() {
       SomeOtherMethod();
    }


protected void SomeOtherMethod() {
  // do something
}

Then, in the child class:

 protected new void MethodToExtend() {
       SomeOtherMethod();
       // do more stuff
    }

var obj = new B();
obj.Print(); // overriden method
(obj as A).Print(); // base method