Csharp/C Sharp/Class Interface/Overloading Method

Illustrates method overloading

/*
Mastering Visual C# .NET
by Jason Price, Mike Gunderloy
Publisher: Sybex;
ISBN: 0782129110
*/
/*
  Example5_9.cs illustrates method overloading
*/

// declare the Swapper class
class Swapper
{
  // this Swap() method swaps two int parameters
  public void Swap(ref int x, ref int y)
  {
    int temp = x;
    x = y;
    y = temp;
  }
  // this Swap() method swaps two float parameters
  public void Swap(ref float x, ref float y)
  {
    float temp = x;
    x = y;
    y = temp;
  }
}

public class Example5_9
{
  public static void Main()
  {
    // create a Swapper object
    Swapper mySwapper = new Swapper();
    // declare two int variables
    int intValue1 = 2;
    int intValue2 = 5;
    System.Console.WriteLine("initial intValue1 = " + intValue1 +
      ", intValue2 = " + intValue2);
    // swap the two float variables
    // (uses the Swap() method that accepts int parameters)
    mySwapper.Swap(ref intValue1, ref intValue2);
    // display the final values
    System.Console.WriteLine("final   intValue1 = " + intValue1 +
      ", intValue2 = " + intValue2);
    // declare two float variables
    float floatValue1 = 2f;
    float floatValue2 = 5f;
    System.Console.WriteLine("initial floatValue1 = " + floatValue1 +
      ", floatValue2 = " + floatValue2);
    // swap the two float variables
    // (uses the Swap() method that accepts float parameters)
    mySwapper.Swap(ref floatValue1, ref floatValue2);
    // display the final values
    System.Console.WriteLine("final   floatValue1 = " + floatValue1 +
      ", floatValue2 = " + floatValue2);
    mySwapper.Swap(ref floatValue1, ref floatValue2);
  }
}

Operator Overloading

 
using System;

public class Rectangle {
    public int width;
    public int height;
    public Rectangle(int width, int height) {
        this.width = width;
        this.height = height;
    }
    public override string ToString() {
        return "width = " + width + ", height = " + height;
    }
    public static bool operator ==(Rectangle lhs, Rectangle rhs) {
        Console.WriteLine("In operator ==");
        if (lhs.width == rhs.width && lhs.height == rhs.height) {
            return true;
        } else {
            return false;
        }
    }
    public static bool operator !=(Rectangle lhs, Rectangle rhs) {
        Console.WriteLine("In operator !=");
        return !(lhs == rhs);
    }
    public override bool Equals(object obj) {
        Console.WriteLine("In Equals()");
        if (!(obj is Rectangle)) {
            return false;
        } else {
            return this == (Rectangle)obj;
        }
    }
    public static Rectangle operator +(Rectangle lhs, Rectangle rhs) {
        Console.WriteLine("In operator +");
        return new Rectangle(
          lhs.width + rhs.width, lhs.height + rhs.height);
    }
}
class MainClass {
    public static void Main() {
        Rectangle myRectangle = new Rectangle(1, 4);
        Console.WriteLine("myRectangle: " + myRectangle);
        Rectangle myRectangle2 = new Rectangle(1, 4);
        Console.WriteLine("myRectangle2: " + myRectangle2);
        if (myRectangle == myRectangle2) {
            Console.WriteLine(
              "myRectangle is equal to myRectangle2");
        } else {
            Console.WriteLine(
              "myRectangle is not equal to myRectangle2");
        }
        Rectangle myRectangle3 = myRectangle + myRectangle2;
        Console.WriteLine("myRectangle3: " + myRectangle3);
    }
}

Overloaded methods with identical signatures cause compilation errors, even if return types are different.

public class MethodOverloadError
{
   public int Square( int x )
   {
      return x * x;
   }
   public double Square( int y )
   {
      return y * y;
   }
}