// class for 3D vectors of ints, plus test main
#include <iostream.h>

class Vector {
	public:
		// ---- constructors ----

		Vector(int init_x = 0, int init_y = 0, int init_z = 0) 
		// postcondition:  x = init_x, y = init_y, z = init_z
		{
			x = init_x; y = init_y; z = init_z;
		}

		// ---- "constant" member functions ----
		
		int get_x(void) const
		// postcondition:  return value is x coordinate
		{
			return x;
		}
			
		int get_y(void) const
		// postcondition:  return value is y coordinate
		{
			return y;
		}

		int get_z(void) const
		// postcondition:  return value is z coordinate
		{
			return z;
		}

		void show(char identifier[]) const
		// postcondition:  x, y, z coordinates printed to cout,
		//	preceded by identifier and followed by endl
		{
			cout << identifier << " = (";
			cout << x << ", " << y << ", " << z;
			cout << ")\n";
		}


	private:
		int x, y, z;
};

// ---- nonmember functions ----

int add(int x, int y)
// postcondition:  return value is x + y
{ return x + y; }

int subtract(int x, int y)
// postcondition:  return value is x - y
{ return x - y; }

Vector pairwiseOperator(const Vector & v1, const Vector & v2,
	int oper(const int, const int))
// postcondition:  return value is produced by combining corresponding
//	elements of v1, v2 using oper
{
	return Vector(oper(v1.get_x(), v2.get_x()),
		oper(v1.get_y(), v2.get_y()),
		oper(v1.get_z(), v2.get_z()));
}

Vector add(const Vector & v1, const Vector & v2)
// postcondition:  return value is sum of v1 and v2
{
	return pairwiseOperator(v1, v2, add);
}

Vector subtract(const Vector & v1, const Vector & v2)
// postcondition:  return value is difference of v1 and v2
{
	return pairwiseOperator(v1, v2, subtract);
}

// ---- main program to test a few things ----

int main()
{
	Vector v1 = Vector(1, 2, 3);
	Vector v2 = Vector(2, 4, 6);
	Vector vtemp;

	v1.show("v1");
	v2.show("v2");

	vtemp = add(v1, v2);
	vtemp.show("v1 + v2");

	vtemp = subtract(v1, v2);
	vtemp.show("v1 - v2");

	return 0;

}