C++初始化参数列表对成员函数初始化

#include <iostream>
using namespace std;
class Desk{
public:
    Desk();//声明一个无参的构造函数
    /*声明一个有参的构造函数，并用参数的初始化列表对数据成员初始化*/
    Desk(int h,int w,int l):height(h),width(w),length(l){}
    int volume();
private:
    int height,width,length;
};
Desk::Desk(){//定义无参的构造函数
    height=2;
    width=3;
    length=4;
}
int Desk::volume(){
    return height*width*length;
}
int main(){
    Desk desk1;//不指定实参
    cout<<"desk1's volume: "<<desk1.volume()<<endl;
    Desk desk2(1,5,5);//指定实参
    cout<<"desk2's volume: "<<desk2.volume()<<endl;
    return 0;
}