C/C++ Source Codes

A class may be DERIVED from another class.

//A class may be DERIVED from another class. The new class INHERITS
//the variables and methods of the BASE CLASS. Additional variables
// and/or methods can be added :
#include <iostream.h>
#include <math.h>
class vector
{
public:
double x;
double y;
vector (double a = 0, double b = 0)
{
x = a;
y = b;
}
double module()
{
return sqrt (x*x + y*y);
}
double surface()
{
return x * y;
}
};
class trivector : public vector // trivector is derived from vector
{
public:
double z; // added to x and y from vector
trivector (double m=0, double n=0, double p=0) : vector (m, n)
{
z = p; // Vector constructor will
} // be called before trivector
// constructor, with parameters
// m and n.
trivector (vector a) // What to do if a vector is
{ // cast to a trivector
x = a.x;
y = a.y;
z = 0;
}
double module () // define module() for trivector
{
return sqrt (x*x + y*y + z*z);
}
double volume ()
{
return this->surface() * z; // or x * y * z
}
};
void main()
{
vector a (4, 5);
trivector b (1, 2, 3);
cout << "a (4, 5) b (1, 2, 3) *r = b" << endl << endl;
cout << "Surface of a : " << a.surface() << endl;
cout << "Volume of b : " << b.volume() << endl;
cout << "Surface of base of b : " << b.surface() << endl;
cout << "Module of a : " << a.module() << endl;
cout << "Module of b : " << b.module() << endl;
cout << "Module of base of b : " << b.vector::module() << endl;
trivector k;
k = a; // thanks to trivector(vector) definition
// copy of x and y, k.z = 0
vector j;
j = b; // copy of x and y. b.z leaved out
vector *r;
r = &b;
cout << "Surface of r : " << r->surface() << endl;
cout << "Module of r : " << r->module() << endl;
}

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