Implementing Pure Virtual Functions : virtual function « Class « C++

1. C++
2. Class
3. virtual function

Implementing Pure Virtual Functions

  
#include <iostream>
using namespace std;

class Shape
{
  public:
    Shape(){}
    virtual ~Shape(){}
    virtual double GetArea() = 0;
    virtual double GetPerim()= 0;
    virtual void Draw() = 0;
  private:
};

void Shape::Draw()
{
   cout << "Abstract drawing mechanism!\n";
}

class Circle : public Shape
{
  public:
    Circle(int radius):itsRadius(radius){}
    virtual ~Circle(){}
    double GetArea() { return 3.14 * itsRadius * itsRadius; }
    double GetPerim() { return 2 * 3.14 * itsRadius; }
    void Draw();
  private:
    int itsRadius;
    int itsCircumference;
};

void Circle::Draw()
{
   cout << "Circle drawing routine here!\n";
   Shape::Draw();
}

class Rectangle : public Shape
{
  public:
    Rectangle(int len, int width):
    itsLength(len), itsWidth(width){}
    virtual ~Rectangle(){}
    double GetArea() { return itsLength * itsWidth; }
    double GetPerim() {return 2*itsLength + 2*itsWidth; }
    virtual int GetLength() { return itsLength; }
    virtual int GetWidth() { return itsWidth; }
    void Draw();
  private:
    int itsWidth;
    int itsLength;
};

void Rectangle::Draw(){
   for (int i = 0; i<itsLength; i++){
      for (int j = 0; j<itsWidth; j++)
         cout << "x ";

   cout << "\n";
   }
   Shape::Draw();
}


class Square : public Rectangle
{
  public:
    Square(int len);
    Square(int len, int width);
    virtual ~Square(){}
    double GetPerim() {return 4 * GetLength();}
};

Square::Square(int len):
Rectangle(len,len)
{}

Square::Square(int len, int width):Rectangle(len,width){
   if (GetLength() != GetWidth())
      cout << "Error, not a square... a Rectangle??\n";
}

int main()
{
   Shape * sp;

   sp = new Circle(5);
   sp->Draw();
   delete sp;
   
   sp = new Rectangle(4,6);
   sp->Draw();
   delete sp;
   
   sp = new Square (5);
   sp->Draw();
   delete sp;

   return 0;
}
  
    
  

Related examples in the same category