#include <cstdlib>
#include <iostream>
#include <cassert>
#include <cmath>

#define sqr(a) ((a)*(a))

using namespace std;

const int dim=2;

class POINT
{
	public:
	POINT(double *crds);
	void getCoords(double *crds) const;
	void setCoords(const double *crds);

	private:
	double coords[dim];
};

POINT::POINT(double *crds)
{
	assert(crds != NULL);
	memcpy(coords, crds, dim*sizeof(double));
}
void POINT::getCoords(double *crds) const
{
	assert(crds != NULL);
	memcpy(crds, coords, dim*sizeof(double));
}

void POINT::setCoords(const double *crds)
{
	memcpy(coords, crds, dim*sizeof(double));
	assert(crds != NULL);
}

class BOND
{
	public:
	BOND(POINT *ip1, POINT *ip2);
	void getPoints(POINT *&op1, POINT *&op2);
	private:
	POINT *p1;
	POINT *p2;
};
BOND::BOND(POINT *ip1, POINT *ip2)
{
	p1 = ip1;
	p2 = ip2;
}

void BOND::getPoints(POINT *&op1, POINT *&op2)
{
	op1 = p1;
	op2 = p2;
	return;
}

//--------------------------------------
//
double separation(const double* p1, const double* p2)
{
	double distsq = 0.0f;
	for(int i=0; i < dim; ++i)
		distsq += sqr(p1[i] - p2[i]);
	return sqrt(distsq);
}

double separation(const POINT& p1, const POINT& p2)
{
	double coords1[dim], coords2[dim];
	p1.getCoords(coords1);
	p2.getCoords(coords2);
	return separation(coords1, coords2);
}

double separation(BOND &b1)
{
	POINT *p1, *p2;
	b1.getPoints(p1,p2);
	return separation(*p1,*p2);
}
//--------------------------------------
//
int main()
{
	double coords1[] = {0.0f, 0.0f};
	double coords2[] = {3.0f, 4.0f};
	POINT p1(coords1);
	POINT p2(coords2);
	BOND b(&p1,&p2);

	cout <<"dist = "<<separation(coords1, coords2)<<endl;
	cout <<"dist = "<<separation(p1, p2)<<endl;
	cout <<"dist = "<<separation(b)<<endl;

	return 0;
}