单项选择题

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;