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

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C++ » Class » virtual functionScreenshots 
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 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 * 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
1.virtual function from base and derived classes
2.Virtual function and two subclasses
3.Abstract classes by virtual function with no body
4.Override non-virtual function
5.Illustration of the Use of Virtual Inheritance
6.Using Virtual Methods
7.Multiple Virtual Functions Called in Turn
8.Virtual Copy Constructor
9.virtual functions accessed from pointer
10.virtual functions with person class
11.Call parent virtual function
12.Using Virtual Functions to control the behaviour
13.Pure Virtual Functions as a prototype
14.Virtual Functions Are Hierarchical
15.Virtual function in three level inheritance
16.The Virtual Attribute Is Inherited
17.Virtual Functions and Polymorphism
18.A base class reference is used to access a virtual function
19.Virtual base classes.
20.virtual members
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