What is polymorphism in c#?

Polymorphism means many forms (ability to take more than one form). In Polymorphism poly means “multiple” and morph means “forms” so polymorphism means many forms. Polymorphism provides following features: 

  • It allows you to invoke methods of derived class through base class reference during runtime.
  • It has the ability for classes to provide different implementations of methods that are called through the same name.
In polymorphism we will declare methods with same name and different parameters in same class or methods with same name and same parameters in different classes. Polymorphism has ability to provide different implementation of methods that are implemented with same name.

Types of polymorphism-

  • Compile Time Polymorphism (Called as Early Binding or Overloading or static binding)
  • Run Time Polymorphism (Called as Late Binding or Overriding or dynamic binding)

Compile Time Polymorphism

Compile time polymorphism means we will declare methods with same name but different signatures because of this we will perform different tasks with same method name. This compile time polymorphism also called as early binding or method overloading.

Method Overloading or compile time polymorphism means same method names with different signatures (different parameters)

Example

In below class we have two methods with same name but having different input parameters this is called method overloading or compile time polymorphism or early binding.

public class Class1
    {
        public void NumbersAdd(int a, int b)
        {
            Console.WriteLine(a + b);
        }
        public void NumbersAdd(int a, int b, int c)
        {
            Console.WriteLine(a + b + c);
        }
    }

Run Time Polymorphism

Run time polymorphism also called as late binding or method overriding or dynamic polymorphism. Run time polymorphism or method overriding means same method names with same signatures.
In this run time polymorphism or method overriding we can override a method in base class by creating similar function in derived class this can be achieved by using inheritance principle and using “virtual & override” keywords.
In base class if we declare methods with virtual keyword then only we can override those methods in derived class using override keyword

Example

 //Base Class
    public class Bclass
    {
        public virtual void Sample1()
        {
            Console.WriteLine("Base Class");
        }
    }
    // Derived Class
    public class DClass : Bclass
    {
        public override void Sample1()
        {
            Console.WriteLine("Derived Class");
        }
    }
    // Using base and derived class
    class Program
    {
        static void Main(string[] args)
        {
            // calling the overriden method
            DClass objDc = new DClass();
            objDc.Sample1();
            // calling the base class method
            Bclass objBc = new DClass();
            objBc.Sample1();
        }
    }

Output


Output

Derived Class
Derived Class
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