C#-Inheritance

Inheritance in C#

C#-Inheritance allows us to define a class based on another class. This makes creating and maintaining an application easy.

When creating a class, instead of writing completely new data members and member functions, the programmer can designate that the new class should inherit the members of an existing class. This existing class is called the base class, and the new class is referred to as the derived class.


Base and Derived Classes:

The class whose properties are inherited by another class is called the Base class. The class which inherits the properties is called the Derived class.


The syntax used in C# for creating derived classes is as follows :

<acess-specifier> class <base_class> {
   ...
}

class <derived_class> : <base_class> {
   ...
}

Consider a base class Shape and its derived class Rectangle :

using System;
namespace InheritanceApplication {
   class Shape {
      public void setWidth(int w) {
         width = w;
      }
      public void setHeight(int h) {
         height = h;
      }
      protected int width;
      protected int height;
   }

   // Derived class
   class Rectangle: Shape {
      public int getArea() { 
         return (width * height); 
      }
   }
   class RectangleTester {
      static void Main(string[] args) {
         Rectangle Rect = new Rectangle();

         Rect.setWidth(5);
         Rect.setHeight(7);

         // Print the area of the object.
         Console.WriteLine("Total area: {0}",  Rect.getArea());
         Console.ReadKey();
      }
   }
}

Initializing Base Class:

The derived class inherits the base class member variables and member methods. Therefore the super class object should be created before the subclass is created. You can give instructions for superclass initialization in the member initialization list.

Example :

using System;
namespace RectangleApplication {
   class Rectangle {
      
      //member variables
      protected double length;
      protected double width;
      
      public Rectangle(double l, double w) {
         length = l;
         width = w;
      }
      public double GetArea() {
         return length * width;
      }
      public void Display() {
         Console.WriteLine("Length: {0}", length);
         Console.WriteLine("Width: {0}", width);
         Console.WriteLine("Area: {0}", GetArea());
      }
   }//end class Rectangle  
   class Tabletop : Rectangle {
      private double cost;
      public Tabletop(double l, double w) : base(l, w) { }
      
      public double GetCost() {
         double cost;
         cost = GetArea() * 70;
         return cost;
      }
      public void Display() {
         base.Display();
         Console.WriteLine("Cost: {0}", GetCost());
      }
   }
   class ExecuteRectangle {
      static void Main(string[] args) {
         Tabletop t = new Tabletop(4.5, 7.5);
         t.Display();
         Console.ReadLine();
      }
   }
}

Multiple C#-Inheritance :

C# does not support multiple inheritance. However, you can use interfaces to implement multiple inheritance.

Example :

using System;

namespace InheritanceApplication {
   class Shape {
      public void setWidth(int w) {
         width = w;
      }
      public void setHeight(int h) {
         height = h;
      }
      protected int width;
      protected int height;
   }

   // Base class PaintCost
   public interface PaintCost {
      int getCost(int area);
   }
   
   // Derived class
   class Rectangle : Shape, PaintCost {
      public int getArea() {
         return (width * height);
      }
      public int getCost(int area) {
         return area * 70;
      }
   }
   class RectangleTester {
      static void Main(string[] args) {
         Rectangle Rect = new Rectangle();
         int area;
         
         Rect.setWidth(5);
         Rect.setHeight(7);
         area = Rect.getArea();
         
         // Print the area of the object.
         Console.WriteLine("Total area: {0}",  Rect.getArea());
         Console.WriteLine("Total paint cost: 
using System;
namespace InheritanceApplication {
class Shape {
public void setWidth(int w) {
width = w;
}
public void setHeight(int h) {
height = h;
}
protected int width;
protected int height;
}
// Base class PaintCost
public interface PaintCost {
int getCost(int area);
}
// Derived class
class Rectangle : Shape, PaintCost {
public int getArea() {
return (width * height);
}
public int getCost(int area) {
return area * 70;
}
}
class RectangleTester {
static void Main(string[] args) {
Rectangle Rect = new Rectangle();
int area;
Rect.setWidth(5);
Rect.setHeight(7);
area = Rect.getArea();
// Print the area of the object.
Console.WriteLine("Total area: {0}",  Rect.getArea());
Console.WriteLine("Total paint cost: ${0}" , Rect.getCost(area));
Console.ReadKey();
}
}
}
" , Rect.getCost(area)); Console.ReadKey(); } } }

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