Polymorphism in C# Explained

Polymorphism means an ability to take more than one form and it’s one of the main pillar of object-oriented programming concepts, after encapsulation and inheritance.

 

Polymorphism is a OOPs concept where one name can have many forms.

For example, you have a smartphone for communication. The communication mode you choose could be anything. It can be a call, a text message, a picture message, mail, etc. So, the goal is common that is communication, but their approach is different. This is called Polymorphism.

Generally, the polymorphism is a combination of two words, one is poly and another one is morphs. Here poly means “multiple” and morphs means “forms” so polymorphism means many forms.

 Polymorphism in C# provides an ability for the classes to implement different methods that are called through the same name and it also provides an ability to invoke the methods of a derived class through base class reference during runtime based on our requirements.

 We have two different kinds of polymorphisms available in C#, these are

 1. Compile Time Polymorphism

2. Run Time Polymorphism

Compile Time Polymorphism

Compile Time Polymorphism means defining multiple methods with the same name but with different parameters. By using compile-time polymorphism, we can perform different tasks with the same method name by passing different parameters.

 The compile-time polymorphism can be achieved by using method overloading and it is also called early binding or static binding.

 The following is the code snippet for implementing a method overloading to achieve compile-time polymorphism in c#.

     public class Calculate

    {

        public void AddNumbers(int a, int b)

        {

            Console.WriteLine($"{a} + {b} = {a + b}");

        }

        public void AddNumbers(int a, int b, int c)

        {

            Console.WriteLine($"{a} + {b} + {c} = {a + b + c}");

        }

    }

If we observe above “Calculate” class closely, we will find out we defined two methods with same name (AddNumbers) but with different input parameters to achieve method overloading, this is called a compile time polymorphism in C#

 

Compile Time Polymorphism Example

Below is the example of implementing a compile-time polymorphism in C#.

 using System;

namespace CsharpnaijaTutorial

{

    public class Calculate

    {

        public void AddNumbers(int a, int b)

        {

            Console.WriteLine($"{a} + {b} = {a + b}");

        }

        public void AddNumbers(int a, int b, int c)

        {

            Console.WriteLine($"{a} + {b} + {c} = {a + b + c}");

        }

    }

    class Program

    {

        static void Main(string[] args)

        {

            Calculate calculate = new Calculate();

            calculate.AddNumbers(1, 2);

            calculate.AddNumbers(1, 2, 3);

            Console.WriteLine("\nPress Enter Key to Exit..");

            Console.ReadLine();

        }

    }

 

}

 

Run Time Polymorphism

 

Run Time Polymorphism means overriding a base class method in the derived class by creating a similar function and this can be achieved by using override & virtual keywords along with inheritance principle.

 

By using run-time polymorphism, we can override a base class method in the derived class by creating a method with the same name and parameters to perform a different task.

 

The run time polymorphism can be achieved by using method overriding and it is also called late binding or dynamic binding.

 

Below is the code snippet for implementing a method overriding to achieve run time polymorphism.

 

   // Base Class

    public class Users

    {

        public virtual void GetInfo()

        {

            Console.WriteLine("Base Class");

        }

    }

    // Derived Class

    public class Details : Users

    {

        public override void GetInfo()

        {

            Console.WriteLine("Derived Class");

        }

    }

  

If we observe above code snippet, we will find out that we created two classes Users and Details. The derived class (Details) is inheriting the properties from base class (Users) and we are overriding the base class method GetInfo in derived class by creating the same function to achieve method overriding, this is called a run time polymorphism.

 

We defined a GetInfo method with a virtual keyword in the base class to allow derived class to override that method using the override keyword.

 

Generally, only the methods with a virtual keyword in the base class are allowed to override in derived class using override keyword.

 

Run Time Example of Polymorphism

The code below shows the example of implementing a run time polymorphism in C#.

 

//using System;

namespace CSharpnaijaTutorial

{

    // Base Class

    public class BaseClass

    {

        public virtual void GetInfo()

        {

            Console.WriteLine("Learn C# Tutorial");

        }

    }

    // Derived Class

    public class DerivedClass : BaseClass

    {

        public override void GetInfo()

        {

            Console.WriteLine("Welcome to Csharpnaija Blog");

        }

    }

    class Program

    {

        static void Main(string[] args)

        {

            DerivedClass derived = new DerivedClass();

            derived.GetInfo();

            BaseClass baseClass = new BaseClass();

            baseClass.GetInfo();

            Console.WriteLine("\nPress Enter Key to Exit..");

            Console.ReadLine();

        }

    }

}

 

Thank you

 

References

1.     Tutlane

2.     Guru99