例4

//【例4.1】商品类对象应用实例。

#include<iostream>#include<iomanip>#include<cstring>using namespace std;class CGoods{private :char Name[21] ;int Amount ;float Price ;float Total_value ;public :void RegisterGoods(char name[],int num,float price) ;void CountTotal() ;void GetName(char name[]) ;int GetAmount() ;float GetPrice() ;float GetTotal_value() ;};void CGoods::RegisterGoods(char name[] , int amount , float price){strcpy(Name , name) ; Amount=amount ; Price=price ;}void CGoods::CountTotal(void){Total_value = Price*Amount;}void CGoods::GetName(char name[]){strcpy(name , Name);}int CGoods::GetAmount(void){return(Amount) ;}float CGoods::GetPrice(void){return(Price) ;}float CGoods::GetTotal_value(void){return(Total_value) ;}int main( ){CGoods car ;char str[21] ;int number ;float pr ;cout<<"请输入汽车型号：" ;cin.getline(str , 20) ; //输入串长必须小于20cout<<"请依次输入汽车数量与单价：" ;cin>>number>>pr ;car.RegisterGoods(str , number , pr) ;car.CountTotal() ;str[0]='\0' ; //字符串str清零car.GetName(str) ; //string赋值cout<<setw(20)<<str<<setw(5)<<car.GetAmount() ; //Acout<<setw(10)<<car.GetPrice()<<setw(20)<<car.GetTotal_value()<<endl ; //B return 0;}//【例4.1_1】完整商品类对象应用实例。

#include<iostream>#include<iomanip>#include<cstring>using namespace std;class CGoods{private :char Name[21] ;int Amount ;float Price ;float Total_value ;public :CGoods();CGoods(char [],int,float);CGoods(char [],float);void RegisterGoods(char[],int,float) ;void CountTotal(void) ;void GetName(char[]) ;int GetAmount(void) ;float GetPrice(void) ;float GetTotal_value(void) ;};CGoods::CGoods(){Name[0]='\0' ; Price=0.0 ;Amount=0 ; Total_value=0.0 ;}CGoods::CGoods(char name[] , int amount , float price){strcpy(Name,name) ; Price=price ;Amount=amount ; Total_value=price*amount ;}CGoods::CGoods(char name[] , float price){strcpy(Name,name) ; Price=price ;Amount=0 ; Total_value=0.0 ;}void CGoods::RegisterGoods(char name[] , int amount , float price){ strcpy(Name , name) ;//字符串拷贝函数Amount=amount ; Price=price ;}void CGoods::CountTotal(void){Total_value = Price*Amount;}void CGoods::GetName(char name[]){strcpy(name , Name);}int CGoods::GetAmount(void){return(Amount) ;}float CGoods::GetPrice(void){return(Price) ;}float CGoods::GetTotal_value(void){return(Total_value) ;}int main( ){char string[21]={'\0'};CGoods Car1("夏利2000",30,98000.0);CGoods Car2("桑塔那2000",164000.0);Car1.GetName(string); //string赋值cout<<setw(20)<<string<<setw(5)<< Car1.GetAmount();cout<<setw(10)<<Car1.GetPrice()<<setw(20)<< Car1.GetTotal_value()<<endl;Car2.GetName(string); //string赋值cout<<setw(20)<<string<<setw(5)<< Car2.GetAmount();cout<<setw(10)<<Car2.GetPrice()<<setw(20)<< Car2.GetTotal_value()<<endl;return 0;}//【例4.2】矩形类。

要确定一个矩形（四边都是水平或垂直方向，不能倾斜），只要确定其左上角和右下角的//x和y坐标即可，因此应包括四个数据成员，left,right,top,bottom，即左右上下四个边界值。

由构造函数对//数据成员赋值。

赋值函数完成未初始化的矩形赋值，也可以修改各数据成员。

并用多文件实现。

#include <iostream>#include "rect.h"using namespace std;int main(){Rectangle rect;cout<<"由默认的构造函数生成的rect："<<endl;rect.Show();rect.Assign(100,200,300,400);cout<<"由赋值函数处理后的rect："<<endl;rect.Show();Rectangle rect1(0,0,200,200);cout<<"由构造函数生成的rect1："<<endl;rect1.Show();return 0;}#include <iostream>#include "rect.h"using namespace std;Rectangle::Rectangle(int l , int t, int r, int b) {left = l; top = t;right = r; bottom = b; } // 构造函数，带默认参数，缺省值为全0，在声明中指定void Rectangle::Assign(int l, int t, int r, int b){left = l; top = t;right = r; bottom = b;}void Rectangle::Show(){cout<<"left-top point is ("<<left<<","<<top<<")"<<'\n';cout<<"right-bottom point is ("<<right<<","<<bottom<<")"<<'\n';}class Rectangle {int left, top ;int right, bottom;public:Rectangle(int l=0, int t=0, int r=0, int b=0);~Rectangle(){}; //析构函数，在此函数体为空void Assign(int l, int t, int r, int b);void SetLeft(int t){ left = t;} // 以下四个函数皆为内联成员函数void SetRight( int t ){ right = t;}void SetTop( int t ){ top = t;}void SetBottom( int t ){ bottom = t;}void Show();};//【例4.3】使用一个函数来交换两个数据。

请对比【例3.10】。

#include<iostream>using namespace std;void swap(double &d1,double &d2){double temp ;temp=d1 ; d1=d2 ; d2=temp ;}int main(void){double x , y ;cout<<"请输入x和y的值"<<'\n';cin>>x>>y ;cout<<"x="<<x<<'\t'<<"y="<<y<<'\n';swap(x,y) ;cout<<"x="<<x<<'\t'<<"y="<<y<<'\n';return 0;}/【例4.4】采用不同返回方式的求正方形面积函数的比较。