急~！！求简单C++编程题答案

Question

五、 编程题(3题×10分=30分)
1. 编写一个抽象类Shape，在此基础上派生出类Rectangle和Circle，二者都有计算对象面积的函数GetArea（）、计算对象周长的函数GetPerim（）。
2. 定义Boat与Car两个类，二者都有weight属性，定义二者的一个友元函数totalWeight( )，计算二者的重量和。
3. 用函数模板实现myswap(x,y),函数功能为交换x和y的值。

Answer 1

第一题
#include <iostream.h>
class Shape
{
public:
float r;
float w,h;
};
class Circle:public Shape
{
public:
double GetArea(float r)
{
return (3.14*r*r);
}
double GetPerim(float r)
{
return (3.14*2*r);
}
};
class Retangle:public Shape
{
public:
float GetArea(float w,float h)
{
return (w*h);
}
float GetPerim(float w,float h)
{
return ((h+w)*2);
}
};
void main()
{
char option;
do
{
cout<<"Please select the shape you want "<<endl;
cout<<"1.Retangle"<<endl;
cout<<"2.Cicle"<<endl;
cout<<"Your option is :";
int selection;
cin>>selection;
for(int i=0;selection!=1&&selection!=2;i++)
{
cout<<"Input error!, please input again ";
}
Retangle retangle;
Circle circle;
if(selection==1)
{
cout<<"Please input width and height ";
cin>>retangle.h>>retangle.w;
cout<<"The area of retangle is "<<retangle.GetArea(retangle.h,retangle.w)<<endl;
cout<<"The perim of retangle is "<<retangle.GetPerim(retangle.h,retangle.w)<<endl;
}
else if(selection==2)
{
cout<<"Please input radius of the circle ";
cin>>circle.r;
cout<<"The area of circle is "<<circle.GetArea(circle.r)<<endl;
cout<<"The perim of circle is "<<circle.GetPerim(circle.r)<<endl;
}
cout<<"Do you want to continue ?, input y or Y means yes ";
cin>>option;
}while(option=='y'||option=='Y');
}
第二题
#include <iostream.h>
class Boat
{
public:
float x;
friend float totalWeight();
};
class Car
{
public:
float y;
friend float totalWeight();
};
float totalWeight(float x,float y)
{
return (x+y);
}
void main()
{
Boat boat;
Car car;
cout<<"please input boat`s weight and car`s weight"<<endl;
cin>>boat.x>>car.y;
cout<<"The total weight of them is "<<totalWeight(boat.x,car.y)<<endl;
}
第三题
头文件
#ifndef ORIGIN_H
#define ORIGIN_H
template <typename T>
T origin(T x)
{
return x;
}
#endif
#ifndef SWAP_H
#define SWAP_H
template <typename T>
T myswap(T x,T y)
{
T temp;
temp=x;
x=y;
y=temp;
return x;
}
#endif
CPP文件
#include "er.h"
#include <iostream.h>
void main()
{
int a,b;
cout<<"Please input two integer:"<<endl;
cin>>a>>b;
cout<<myswap(a,b)<<" "<<origin(a)<<endl;
float c,d;
cout<<"Please input two float :"<<endl;
cin>>c>>d;
cout<<myswap(c,d)<<" "<<origin(c)<<endl;
char e,f;
cout<<"Please input two char :"<<endl;
cin>>e>>f;
cout<<myswap(e,f)<<" "<<origin(e)<<endl;
}

Answer 2

class Shape
{
public:
Shape(){}
~Shape(){}
virtual float GetArea() = 0; //定义纯虚函数
virtual float GetPerim() = 0;
}

class Rectangle : public Shape
{
private:
float m_fLength;
float m_fWidth;
public:

Rectangle(float fLength,float fWidth){
m_fLength = fLength;
m_fWidth = fWidth;
}
~Rectangle(){}
float GetArea(){
return m_fWidth*m_fLength;
}
float GetPerim(){
return 2*(m_fWidth+m_fLength);
}

}
#define PI 3.1415926
class Circle : public Shape
{
private:
float m_fDiameter;
public:
Circle(float fDiameter){
m_fDiameter = fDiameter;
}
~Circle(){}
float GetArea(){
return PI*(m_fDiameter*m_fDiameter)/4;
}
float GetPerim(){
return PI*m_fDiameter;
}

}