3-4 计算长方形的周长和面积

3-4 计算长方形的周长和面积

Time Limit: 1000MS Memory limit: 65536K

题目描述

通过本题的练习可以掌握拷贝构造函数的定义和使用方法；
设计一个长方形类Rect，计算长方形的周长与面积。类中有私有数据成员Length(长)、Width(宽)，由具有缺省参数值的构造函数对其初始化，函数原型为：Rect(double Length=0, double Width=0); 再为其定义拷贝构造函数，形参为对象的常引用，函数原型为：Rect(const Rect &); 编写主函数，创建Rect对象r1初始化为长、宽数据，利用r1初始化另一个Rect对象r2，分别输出对象的长和宽、周长和面积。

要求： 创建对象 Rect r1(3.0,2.0),r2(r1);

输入

输入两个实数，中间用一个空格间隔；代表长方形的长和宽

输出

共有6行
；

分别输出r1的长和宽；
r1的周长；
r1的面积；r2的长和宽；
r2的周长；
r2的面积；注意单词与单词之间用一个空格间隔

示例输入

56 32

示例输出

the length and width of r1 is:56,32
the perimeter of r1 is:176
the area of r1 is:1792
the length and width of r2 is:56,32
the perimeter of r2 is:176
the area of r2 is:1792

提示

输入
-7.0 -8.0

输出

the length and width of r1 is:0,0

the perimeter
of r1 is:0

the area of
r1 is:0

the length and
width of r2 is:0,0

the perimeter
of r2 is:0

the area of
r2 is:0

#include <iostream>
using namespace std;

class box
{
private:
double l,w;
public:
box(double=0,double=0);
double s();
double c();
};
box::box(double len,double wide)
{
l=len;
w=wide;
}
double box::s()
{
return l*w;
}
double box::c()
{
return 2*(l+w);
}
int main()
{
double n,m;
cin>>n>>m;
if(n<=0 ||m<=0)
{
cout <<"the length and width of r1 is:0,0"<<endl;
cout <<"the perimeter of r1 is:0"<<endl;
cout <<"the area of r1 is:0"<<endl;
cout <<"the length and width of r2 is:0,0"<<endl;
cout <<"the perimeter of r2 is:0"<<endl;
cout <<"the area of r2 is:0"<<endl;
}
else
{
box box1(n,m);
cout <<"the length and width of r1 is:"<<n<<","<<m<<endl;
cout <<"the perimeter of r1 is:"<<box1.c()<<endl;
cout <<"the area of r1 is:"<<box1.s()<<endl;
box box2(box1);
cout <<"the length and width of r2 is:"<<n<<","<<m<<endl;
cout <<"the perimeter of r2 is:"<<box2.c()<<endl;
cout <<"the area of r2 is:"<<box2.s()<<endl;
}
return 0;
}