13周 acm

#include <iostream>#include <cstdio>#include <cmath>#include <iomanip>using namespace std;class Point{public:    Point(double a=0,double b=0,double c=0,double d=0):x1(a),y1(b),x2(c),y2(d) {}    void  input();    friend void output(Point &);private:    double x1;    double y1;    double x2;    double y2;};void Point::input(){    cin>>x1>>y1>>x2>>y2;}void output(Point &p){    double d;    d=sqrt((p.x1-p.x2)*(p.x1-p.x2)+(p.y1-p.y2)*(p.y1-p.y2));    cout<<setiosflags(ios::fixed)<<setprecision(2)<<"There are "<<d<<" meters between xiaohui and her phone."<<endl;}int main(){    Point p1;    p1.input();    output(p1);    return 0;}