A class can be derived from more than one base class

NOTE : -

THIS CONTENT IS NOT ORIGINAL

28. A class can be derived from more than one base class

Maybe you wonder if a class can be derived from more than one base class. The answer is yes:

using namespace std;
#include 
#include 

class vector
{
public:

  double x;
  double y;

  vector (double a = 0, double b = 0)
  {
     x = a;
     y = b;
  }

  double surface()
  {
     return fabs (x * y);
  }
};

class number
{
public:

  double z;

  number (double a)
  {
     z = a;
  }

  int is_negative ()
  {
     if (z < 0) return 1;
     else       return 0;
  }
};

class trivector: public vector, public number
{
public:

  trivector(double a=0, double b=0, double c=0): vector(a,b), number(c)
  {
  }           // The trivector constructor calls the vector
              // constructor, then the number constructor,
              // and in this example does nothing more.

  double volume()
  {
     return fabs (x * y * z);
  }
};

int main ()
{
  trivector a(2, 3, -4);

  cout << a.volume() << endl;
  cout << a.surface() << endl;
  cout << a.is_negative() << endl;

  return 0;
}

Output

24 6 1

BIBILOGRAPHY / REFERENCE : - http://www.4p8.com/eric.brasseur/cppcen.html