Part 2 object oriented

Structure 8 inheritance, overload, polymorphism, virtual function

Catalog

1 inheritance

#include <iostream>

using namespace std;

// Base class
class Shape 
{
   public:
      void setWidth(int w)
      {
         width = w;
      }
      void setHeight(int h)
      {
         height = h;
      }
   protected:
      int width;
      int height;
};

// Derived class
class Rectangle: public Shape
{
   public:
      int getArea()
      { 
         return (width * height); 
      }
};

int main(void)
{
   Rectangle Rect;

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

   // Area of output object
   cout << "Total area: " << Rect.getArea() << endl;

   return 0;
}

When the above code is compiled and executed, it produces the following results:
Total area: 35

#include <iostream>

using namespace std;

// Base class Shape
class Shape 
{
   public:
      void setWidth(int w)
      {
         width = w;
      }
      void setHeight(int h)
      {
         height = h;
      }
   protected:
      int width;
      int height;
};

// Base class PaintCost
class PaintCost 
{
   public:
      int getCost(int area)
      {
         return area * 70;
      }
};

// Derived class
class Rectangle: public Shape, public PaintCost
{
   public:
      int getArea()
      { 
         return (width * height); 
      }
};

int main(void)
{
   Rectangle Rect;
   int area;

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

   area = Rect.getArea();

   // Area of output object
   cout << "Total area: " << Rect.getArea() << endl;

   // Total output cost
   cout << "Total paint cost: $" << Rect.getCost(area) << endl;

   return 0;
}

When the above code is compiled and executed, it produces the following results:
Total area: 35
Total paint cost: $2450

#include <iostream>

using namespace std;
//Base class

class D
{
public:
    D(){cout<<"D()"<<endl;}
    ~D(){cout<<"~D()"<<endl;}
protected:
    int d;
};

class B:virtual public D
{
public:
    B(){cout<<"B()"<<endl;}
    ~B(){cout<<"~B()"<<endl;}
protected:
    int b;
};

class A:virtual public D
{
public:
    A(){cout<<"A()"<<endl;}
    ~A(){cout<<"~A()"<<endl;}
protected:
    int a;
};

class C:public B, public A
{
public:
    C(){cout<<"C()"<<endl;}
    ~C(){cout<<"~C()"<<endl;}
protected:
    int c;
};

int main()
{
    cout << "Hello World!" << endl;
    C c;   //D, B, A ,C
    cout<<sizeof(c)<<endl;
    return 0;
}

Hello World!
D()
B()
A()
C()
40
~C()
~A()
~B()
~D()

2 overloaded operators and overloaded functions

#include <iostream>
using namespace std;

class printData 
{
   public:
      void print(int i) {
        cout << "Integer is: " << i << endl;
      }

      void print(double  f) {
        cout << "Floating point numbers are: " << f << endl;
      }

      void print(string c) {
        cout << "The string is: " << c << endl;
      }
};

int main(void)
{
   printData pd;

   // Output integer
   pd.print(5);
   // Output floating point number
   pd.print(500.263);
   // Output string
   pd.print("Hello C++");

   return 0;
}

When the above code is compiled and executed, it produces the following results:
The integer is: 5
Floating point: 500.263
The string is: Hello C++

#include <iostream>
using namespace std;

class Box
{
   public:

      double getVolume(void)
      {
         return length * breadth * height;
      }
      void setLength( double len )
      {
          length = len;
      }

      void setBreadth( double bre )
      {
          breadth = bre;
      }

      void setHeight( double hei )
      {
          height = hei;
      }
      // Overload + operator, used to add two Box objects
      Box operator+(const Box& b)
      {
         Box box;
         box.length = this->length + b.length;
         box.breadth = this->breadth + b.breadth;
         box.height = this->height + b.height;
         return box;
      }
   private:
      double length;      // length
      double breadth;     // width
      double height;      // height
};
// Main function of program
int main( )
{
   Box Box1;                // Declare Box1, type Box
   Box Box2;                // Declare Box2 of type Box
   Box Box3;                // Declare Box3, type Box
   double volume = 0.0;     // Store volume in this variable

   // Box1 details
   Box1.setLength(6.0); 
   Box1.setBreadth(7.0); 
   Box1.setHeight(5.0);

   // Box2 details
   Box2.setLength(12.0); 
   Box2.setBreadth(13.0); 
   Box2.setHeight(10.0);

   // Volume of Box1
   volume = Box1.getVolume();
   cout << "Volume of Box1 : " << volume <<endl;

   // Volume of Box2
   volume = Box2.getVolume();
   cout << "Volume of Box2 : " << volume <<endl;

   // Add the two objects to get Box3
   Box3 = Box1 + Box2;

   // Volume of Box3
   volume = Box3.getVolume();
   cout << "Volume of Box3 : " << volume <<endl;

   return 0;
}

When the above code is compiled and executed, it produces the following results:
Volume of Box1 : 210
Volume of Box2 : 1560
Volume of Box3 : 5400

Unary operator overload

#include <iostream>
using namespace std;

class Distance
{
   private:
      int feet;             // 0 to infinity
      int inches;           // 0 to 12
   public:
      // Required constructor
      Distance(){
         feet = 0;
         inches = 0;
      }
      Distance(int f, int i){
         feet = f;
         inches = i;
      }
      // How to display distance
      void displayDistance()
      {
         cout << "F: " << feet << " I:" << inches <<endl;
      }
      // Overload negative operator (-)
      Distance operator- ()  
      {
         feet = -feet;
         inches = -inches;
         return Distance(feet, inches);
      }
};
int main()
{
   Distance D1(11, 10), D2(-5, 11);

   -D1;                     // Take the opposite number
   D1.displayDistance();    // Distance D1

   -D2;                     // Take the opposite number
   D2.displayDistance();    // Distance D2

   return 0;
}

When the above code is compiled and executed, it produces the following results:
F: -11 I:-10
F: 5 I:-11

Binary operator overload

Calculate the volume of Box3 above (the same code)

3 polymorphism and virtual function

#include <iostream> 
using namespace std;

class Shape {
   protected:
      int width, height;
   public:
      Shape( int a=0, int b=0)
      {
         width = a;
         height = b;
      }
      int area()
      {
         cout << "Parent class area :" <<endl;
         return 0;
      }
};
class Rectangle: public Shape{
   public:
      Rectangle( int a=0, int b=0):Shape(a, b) { }
      int area ()
      { 
         cout << "Rectangle class area :" <<endl;
         return (width * height); 
      }
};
class Triangle: public Shape{
   public:
      Triangle( int a=0, int b=0):Shape(a, b) { }
      int area ()
      { 
         cout << "Triangle class area :" <<endl;
         return (width * height / 2); 
      }
};
// Main function of program
int main( )
{
   Shape *shape;
   Rectangle rec(10,7);
   Triangle  tri(10,5);

   // Address of the storage rectangle
   shape = &rec;
   // Calling area function of rectangle
   shape->area();

   // Storage triangle address
   shape = &tri;
   // Call area function of triangle
   shape->area();

   return 0;
}