COMPUTER INNOVATIONS: C++ Pointers & functions pro

Pointer to derived objects

#include

#include

#include

using namespace std;

class b_class

  char author[80];

public:

  void put_author(char *s)

   strcpy(author, s);

  void show_author()

   cout << author << "\n";

} ;

class d_class : public b_class

  char title[80];

public:

  void put_title(char *num)

    strcpy(title, num);

  void show_title()

    cout << "Title: ";

    cout <<  title << "\n";

};

int main()

  b_class *p;

  b_class b_ob;

  d_class *dp;

  d_class d_ob;

  p = &b_ob;

  p->put_author("tom clancy");

  p = &D_ob;

  p->put_author("William Shakespeare");

  b_ob.show_author();

  d_ob.show_author();

  cout << "\n";

  dp = &d_ob;

  dp->put_title("The Tempest");

  p->show_author();

  dp->show_title( );

  return 0;

#include

#include

using namespace std;

class figure

protected:

  double x, y;

public:

  void set_dim(double i, double j=0)

    x = i;

    y = j;

  virtual void show_area()

    cout << "No area computation defined ";

    cout << "for this class.\n";

} ;

class triangle : public figure

  public:

    void show_area()

      cout << "Triangle with height ";

      cout << x << " and base " << y;

      cout << " has an area of ";

      cout << x * 0.5 * y << ".\n";

};

class square : public figure

  public:

    void show_area()

      cout << "Square with dimensions ";

      cout << x << "x" << y;

      cout << " has an area of ";

      cout << x *  y << ".\n";

};

class circle : public figure

  public:

    void show_area()

      cout << "Circle with radius ";

      cout << x;

      cout << " has an area of ";

      cout << 3.14 * x * x << ".\n";

} ;

int main()

  figure *p;

  triangle t;

  square s;

  circle c;

  p = &t;

  p->set_dim(10.0, 5.0);

  p->show_area();

  p = &s;

  p->set_dim(10.0, 5.0);

  p->show_area();

  p = &c;

  p->set_dim(9.0);

  p->show_area();

  return 0;

#include

#include

using namespace std;

int main()

   int Len, Wid;

   int &rLen = Len;

   int &rWid = Wid;

   Len = 10;

   Wid = 20;

   cout << "Len is: " << Len << ", and  Wid is: " << Wid << endl;

   cout << "rLen is: " << rLen << ", and rWid is: " << rWid << endl;

   cout << endl;

   cout << "Address of Len is: " << &Len << endl;

   cout << "Address of rLen is: "  << &rLen << endl;

   if(&Len == &rLen)

               cout << "Address of Len is equal to address of rLen!" << endl;

   cout << "Address of Wid is: " << &Wid << endl;

   cout << "Address of rWid is: "  << &rWid << endl;

   if(&Wid == &Wid)

               cout << "Address of Wid is equal to address of rWid!" << endl;

   return 0;

#include

#include

using namespace std;

void swap(int &i, int &j);

int main()

   int numone = 0;

   int numtwo = 0;

   cout << "Please enter two integers: " << endl;

   cout << "Enter value for NumOne: " ;

   cin >> numone;

   cout << "Enter value for NumTwo: " ;

   cin >> numtwo;

   cout << "Before swapping, NumOne is: " << numone << endl;

   cout << "Before swapping, NumTwo is: " << numtwo<< endl;

   swap(NumOne, NumTwo);

   cout << "After swapping, NumOne is: " << numone << endl;

   cout << "After swapping, NumTwo is: " << numtwo<< endl;

   return 0;

void swap(int &i, int &j)

   int temp;

   temp = i;

   i = j;

   j = temp;