Difference between Method overloading and method overriding with example

 

Method Overloading vs Method Overriding in C#

Method Overloading — Definition:

Method Overloading is a feature in C# where multiple methods can have the same name within the same class but with different parameter lists (different type, number, or order of parameters).

It is also known as:

• Compile Time Polymorphism

• Static Polymorphism

• Early Binding

Method Overriding — Definition:

Method Overriding is a feature in C# where a method in a derived (child) class provides a specific implementation of a method that is already defined in its base (parent) class.

It requires the use of:

• virtual keyword in the base class method

• override keyword in the derived class method

It is also known as:

• Runtime Polymorphism

• Dynamic Polymorphism

• Late Binding

 

Feature	Method Overloading	Method Overriding
Concept	Same method name, but different parameters (compile-time polymorphism)	Same method name, same parameters, but different implementation in derived class (runtime polymorphism)
Class Requirement	Same class or base & derived class	Must have inheritance (base & derived class)
Keywords Used	No keyword needed	virtual in the base class, override in derived class
Parameters	Must be different (number, type, or order)	It must be exactly the same parameters/signature
Polymorphism Type	Compile Time Polymorphism	Runtime Polymorphism
Achieved By	Function Signature Change	Inheritance & overriding base method

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Live Example — Covering all scenarios

using System;

public class Program
{
    public static void Main(string[] args)
    {
        // Method Overloading Example
        Calculator calculator = new Calculator();
        
        Console.WriteLine("Method Overloading Example:");
        Console.WriteLine($"Sum of 10 and 20: {calculator.Add(10, 20)}");
        Console.WriteLine($"Sum of 10, 20 and 30: {calculator.Add(10, 20, 30)}");
        Console.WriteLine();

        // Method Overriding Example
        Animal genericAnimal = new Animal();
        genericAnimal.Speak(); // Output: Animal makes a sound
        
        Animal dog = new Dog(); // Polymorphism - Upcasting
        dog.Speak(); // Output: Dog Barks

        Animal cat = new Cat();
        cat.Speak(); // Output: Cat Meows
    }
}

// Method Overloading Example
public class Calculator
{
    // Add with 2 parameters
    public int Add(int a, int b)
    {
        return a + b;
    }

    // Add with 3 parameters (Overloaded Method)
    public int Add(int a, int b, int c)
    {
        return a + b + c;
    }
}

// Method Overriding Example
public class Animal
{
    // Base method
    public virtual void Speak()
    {
        Console.WriteLine("Animal makes a sound");
    }
}

public class Dog : Animal
{
    // Overriding Speak() method
    public override void Speak()
    {
        Console.WriteLine("Dog Barks");
    }
}

public class Cat : Animal
{
    // Overriding Speak() method
    public override void Speak()
    {
        Console.WriteLine("Cat Meows");
    }
}

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Output:

Method Overloading Example:
Sum of 10 and 20: 30
Sum of 10, 20 and 30: 60

Animal makes a sound
Dog Barks
Cat Meows

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Summary — Key Differences:

Method Overloading	Method Overriding
Same method name but different parameters	Same method name and same parameters
Compile Time Polymorphism	Runtime Polymorphism
No inheritance required	Inheritance is mandatory
Achieved within the same class or derived class	Achieved through virtual & override keywords
Method signature should differ	Method signature must remain the same

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Pro Tip (Interview Point):

• Overloading is used to ensure functionality reusability within the same class.

• Overriding is used for the customized behavior of the base class method in the child class.