定义两个构造函数其中一个有参一个无参

 1 #include <iostream>
 2 
 3 /* run this program using the console pauser or add your own getch, system("pause") or input loop */
 4 using namespace std;
 5 class Box
 6 {
 7     public:
 8         Box();
 9         Box(int h,int w,int len):height(h),width(w),length(len){}
10         int volume();
11     private:
12         int height;
13         int width;
14         int length;
15 };
16     Box::Box()
17     {
18         height=10;
19         width=10;
20         length=10;
21     }
22     int Box::volume()
23     {
24         return(height*width*length);
25     }
26 
27 int main(int argc, char** argv) {
28     
29     Box box1;
30     cout <<"The volume of box1 is "<<box1.volume()<<endl;
31     Box box2(15,30,25);
32     cout<<"The volume of box2 is "<<box2.volume()<<endl;
33     return 0;
34 }