下面程序的输出结果是( )。
#include<iostream>
#include <math.h>
using namespace std;
class point
private:
double x;
double y;
public:
point(double a, double b)
x=a;
y=b;
friend double distances(point a,point b);
;
double distances(point a,point b)
return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
int main()
point p1 (1,2);
point p2(5,2);
cout<<distances(p1 ,p2)<<end1;
return 0;
A) 2
B) 4
C) 8
D) 16