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