C++课本第四章例题

#include <iostream>
using namespace std;
class Clock{
    private :
        int hour,minute,second;
    public:
        void setTime(int hour=0,int minute=0,int second=0);
        void showTime();
};
void Clock::setTime(int newH,int newM,int newS)
{
    hour=newH;
    minute=newM;
    second=newS;
}
void Clock::showTime()
{
    cout<<hour<<"/"<<minute<<"/"<<second<<endl;
}
int main()
{
    Clock myclock;
    myclock.setTime();
    myclock.showTime();
    myclock.setTime(11,2,3);
    myclock.showTime();
}

 1 #include <iostream>
 2 #include <cmath>
 3 using namespace std;
 4 class Point{
 5     public:
 6         Point(int xx=0,int yy=0){
 7             x=xx;
 8             y=yy;
 9         }
10         Point(Point &p);
11         int getx(){
12             return x;
13         }
14         int gety(){
15             return y;
16         }
17     private:
18         int x;
19         int y;
20 };
21 Point::Point(Point &p)
22 {
23     x=p.x;
24     y=p.y;
25     cout<<"copy"<<endl;
26 }
27 class Line{
28     public:
29         Line(Point xp1,Point xp2);
30         Line(Line &l);
31         double getline(){
32             return len;
33         }
34         private:
35             double len;
36             Point p1,p2;        
37 };
38 Line::Line(Point xp1,Point xp2):p1(xp1),p2(xp2){
39     cout<<"line"<<endl;
40     double x=static_cast<double> (p1.getx()-p2.getx());
41     double y=static_cast<double> (p1.gety()-p2.gety());
42     len=sqrt(x*x+y*y);
43 }
44 Line::Line(Line &l):p1(l.p1),p2(l.p2){
45     cout<<"copy line"<<endl;
46     len=l.len;
47 }
48 int main()
49 {
50     Point myp1(1,1),myp2(4,5);
51     Line line(myp1,myp2);
52     Line line2(line);
53     cout<<"the length of the line is:";
54     cout<<line.getline()<<endl;
55     cout<<"the length of the line2 is:";
56     cout<<line2.getline()<<endl;
57     return 0;
58 }