Csharp/CSharp Tutorial/Class/Base Class

Add constructors to base class

using System; 
 
class Shape { 
  double pri_width;  // private 
  double pri_height; // private  
 
  public Shape(double w, double h) { 
    width = w; 
    height = h; 
  } 
 
  // properties for width and height. 
  public double width { 
     get { return pri_width; } 
     set { pri_width = value; } 
  } 
 
  public double height { 
     get { return pri_height; } 
     set { pri_height = value; } 
  } 
 
  public void showDim() { 
    Console.WriteLine("Width and height are " + 
                       width + " and " + height); 
  } 
} 
 
class Triangle : Shape { 
  string style; // private 
   
  public Triangle(string s, double w, double h) : base(w, h) { 
    style = s;  
  } 
 
  // Return area of triangle. 
  public double area() { 
    return width * height / 2; 
  } 
 
  // Display a triangle"s style. 
  public void showStyle() { 
    Console.WriteLine("Triangle is " + style); 
  } 
} 
 
class MainClass { 
  public static void Main() { 
    Triangle t1 = new Triangle("isosceles", 4.0, 4.0); 
    Triangle t2 = new Triangle("right", 8.0, 12.0); 
 
    Console.WriteLine("Info for t1: "); 
    t1.showStyle(); 
    t1.showDim(); 
    Console.WriteLine("Area is " + t1.area()); 
 
    Console.WriteLine(); 
 
    Console.WriteLine("Info for t2: "); 
    t2.showStyle(); 
    t2.showDim(); 
    Console.WriteLine("Area is " + t2.area()); 
  } 
}

Info for t1:
Triangle is isosceles
Width and height are 4 and 4
Area is 8
Info for t2:
Triangle is right
Width and height are 8 and 12
Area is 48

Add more constructors to base class

using System; 
 
class Shape { 
  double pri_width;  // private 
  double pri_height; // private  
 
  public Shape() { 
    width = height = 0.0; 
  } 
 
  // Constructor for Shape. 
  public Shape(double w, double h) { 
    width = w; 
    height = h; 
  } 
 
  // Construct object with equal width and height. 
  public Shape(double x) { 
    width = height = x; 
  } 
 
  // Properties for width and height. 
  public double width { 
     get { return pri_width; } 
     set { pri_width = value; } 
  } 
 
  public double height { 
     get { return pri_height; } 
     set { pri_height = value; } 
  } 
 
  public void showDim() { 
    Console.WriteLine("Width and height are " + 
                       width + " and " + height); 
  } 
} 
 
// A derived class of Shape for triangles. 
class Triangle : Shape { 
  string style; // private 
   
  /* A default constructor. This automatically invokes 
     the default constructor of Shape. */ 
  public Triangle() { 
    style = "null"; 
  } 
 
  // Constructor that takes three arguments. 
  public Triangle(string s, double w, double h) : base(w, h) { 
    style = s;  
  } 
 
  // Construct an isosceles triangle. 
  public Triangle(double x) : base(x) { 
    style = "isosceles";  
  } 
 
  // Return area of triangle. 
  public double area() { 
    return width * height / 2; 
  } 
 
  // Display a triangle"s style. 
  public void showStyle() { 
    Console.WriteLine("Triangle is " + style); 
  } 
} 
 
class MainClass { 
  public static void Main() { 
    Triangle t1 = new Triangle(); 
    Triangle t2 = new Triangle("right", 8.0, 12.0); 
    Triangle t3 = new Triangle(4.0); 
 
    t1 = t2; 
 
    Console.WriteLine("Info for t1: "); 
    t1.showStyle(); 
    t1.showDim(); 
    Console.WriteLine("Area is " + t1.area()); 
 
    Console.WriteLine(); 
 
    Console.WriteLine("Info for t2: "); 
    t2.showStyle(); 
    t2.showDim(); 
    Console.WriteLine("Area is " + t2.area()); 
 
    Console.WriteLine(); 
 
    Console.WriteLine("Info for t3: "); 
    t3.showStyle(); 
    t3.showDim(); 
    Console.WriteLine("Area is " + t3.area()); 
 
    Console.WriteLine(); 
  } 
}

Info for t1:
Triangle is right
Width and height are 8 and 12
Area is 48
Info for t2:
Triangle is right
Width and height are 8 and 12
Area is 48
Info for t3:
Triangle is isosceles
Width and height are 4 and 4
Area is 8

Call constructor in base class

using System;
public class BaseClass
{
    public BaseClass(int x)
    {
        this.x = x;
    }
    public int X
    {
        get
        {
            return(x);
        }
    }
    int    x;
}
public class Derived: BaseClass
{
    public Derived(int x): base(x)
    {
    }
}
class MainClass
{
    public static void Main()
    {
        Derived d = new Derived(15);
        Console.WriteLine("X = {0}", d.X);
    }
}

X = 15

Define base class another cs file

//File: base.cs
using System;

namespace BaseClassNS
{
   public class MyBaseClass
   {
      public void PrintMe()
      {
         Console.WriteLine("I am MyBaseClass");
      }
   }
}
//////////////////////////////////////
//MainClass.cs
using System;
using BaseClassNS;
namespace UsesBaseClass
{
   class DerivedClass : MyBaseClass
   {
   }
   class MainClass
   {
      static void Main()
      {
         DerivedClass mdc = new DerivedClass();
         mdc.PrintMe();
      }
   }
}

Pass a derived class reference to a base class reference.

using System; 
 
class Shape { 
  double pri_width;  // private 
  double pri_height; // private 
 
  public Shape() { 
    width = height = 0.0; 
  } 
 
  public Shape(double w, double h) { 
    width = w; 
    height = h; 
  } 
 
  public Shape(double x) { 
    width = height = x; 
  } 
 
  public Shape(Shape ob) { 
    width = ob.width; 
    height = ob.height; 
  } 
 
  public double width { 
     get { return pri_width; } 
     set { pri_width = value; } 
  } 
 
  public double height { 
     get { return pri_height; } 
     set { pri_height = value; } 
  } 
 
  public void showDim() { 
    Console.WriteLine("Width and height are " + 
                       width + " and " + height); 
  } 
} 
 
class Triangle : Shape { 
  string style; // private 
   
  // A default constructor. 
  public Triangle() { 
    style = "null"; 
  } 
 
  // Constructor for Triangle. 
  public Triangle(string s, double w, double h) : base(w, h) { 
    style = s;  
  } 
 
  // Construct an isosceles triangle. 
  public Triangle(double x) : base(x) { 
    style = "isosceles";  
  } 
 
  // Construct an object from an object. 
  public Triangle(Triangle ob) : base(ob) { 
    style = ob.style; 
  } 
 
  // Return area of triangle. 
  public double area() { 
    return width * height / 2; 
  } 
 
  // Display a triangle"s style. 
  public void showStyle() { 
    Console.WriteLine("Triangle is " + style); 
  } 
} 
 
class MainClass { 
  public static void Main() { 
    Triangle t1 = new Triangle("right", 8.0, 12.0); 
 
    // make a copy of t1 
    Triangle t2 = new Triangle(t1); 
 
    Console.WriteLine("Info for t1: "); 
    t1.showStyle(); 
    t1.showDim(); 
    Console.WriteLine("Area is " + t1.area()); 
 
    Console.WriteLine(); 
 
    Console.WriteLine("Info for t2: "); 
    t2.showStyle(); 
    t2.showDim(); 
    Console.WriteLine("Area is " + t2.area()); 
  } 
}

Info for t1:
Triangle is right
Width and height are 8 and 12
Area is 48
Info for t2:
Triangle is right
Width and height are 8 and 12
Area is 48