Method Overloading, Overriding & Access Modifiers

1. Description

Method overloading: defining multiple methods with the same name but different parameters in the same class. Method overriding: a derived class provides a different implementation of a virtual method from its base class. Access modifiers (public, private, protected, internal) control visibility of types and members.

2. Why It Is Important

Overloading improves API ergonomics. Overriding enables polymorphism so code can call methods on base types and get derived behavior. Access modifiers enforce encapsulation and help design safe, maintainable classes.

3. Real-World Examples

• Overload constructors to allow different ways to create an object.
• Override a Log() method in different logger implementations.
• Use private to hide internal helper methods, public to expose APIs.

4. Syntax & Explanation

using System;

class Logger
{
    public virtual void Log(string message)
    {
        Console.WriteLine($"[Base] {message}");
    }
}

class FileLogger : Logger
{
    public override void Log(string message)
    {
        // Simulate writing to a file (here we print with a tag)
        Console.WriteLine($"[File] {message}");
    }
}

class MathUtils
{
    // Overloaded methods: same name, different parameters
    public int Add(int a, int b) => a + b;
    public double Add(double a, double b) => a + b;
    public int Add(int a, int b, int c) => a + b + c;

    // Access modifiers: private helper
    private void Helper() { /* internal logic */ }
}

class Program
{
    static void Main()
    {
        Logger logger = new FileLogger();
        logger.Log("Hello world"); // Calls override in FileLogger

        var math = new MathUtils();
        Console.WriteLine(math.Add(1, 2));       // 3
        Console.WriteLine(math.Add(1.5, 2.3));   // 3.8
        Console.WriteLine(math.Add(1, 2, 3));    // 6
    }
}

5. Use Cases

• Provide multiple conveniences for API callers (overloads).
• Implement specific behaviors for derived types (overrides).
• Encapsulate internal logic and expose minimal public surface.

6. Mini Practice Task

1. Create a base Shape class with a virtual Area() method and override it in Circle and Rectangle.
2. Add overloads of a Print method that accept int, double, and string.