求距离可以用开平方公式，代码如下，采纳本回答后补充你要求中其他内容：

#include <iostream>
#include <math>
using namespace std;
class point 
{
public:
point(int xx=0,int yy=0){X=xx;Y=yy;}
int getX(){return X;}
int getY(){return Y;}
friend float dist(point &a, point &b);
private:
int X,Y;
};
float dist(point &p1,point &p2)
{
double x=double(p1.X-p2.X);
double y=double(p1.Y-p2.Y);
return float(sqrt(x*x+y*y));
}
int main()
{
point myp1(0,0),myp2(4,4);
cout<<"距离是："<< dist(myp1,myp2) << endl;
}