C++primer plus第六版课后编程题答案10.4

#ifndef SALES_H_
#define SALES_H_	//测试这一句的作用
namespace SALES{
class Sales{
const static int QUARTERS=4;
private:
double sales[QUARTERS];
double average;
double max;
double min;
public:
Sales(const double ar[],int n);
Sales();
void showS(int n){
for(int i=0;i<n;i++)
std::cout<<sales[i]<<" ";//用于方便显示数组内容;
};
void showSales();
};//不能缺少";"??
};
#endif

#include <iostream>
#include "SALES.h"
using namespace std;
//using namespace SALES;
static int m=0;

SALES::Sales::Sales(const double ar[],int n)
{
bool flag=false;//用于判断max,min,avg是否要设置为0；
double Max=-999;
double Min=999;
double Avg=0;
double Sum=0;
if(n<0)
cout<<"\nError input!"<<endl;
if(n>4)
{
n=4;
m=n;
}
if(n<=4&&n>0)
{
m=n;//记得要及时更新m的值，否则showS（m)容易出错
flag=true;//这里就不是设置为0；
for(int i=0;i<n;i++)
{
sales[i]=ar[i];
Sum+=sales[i];
if(Max<sales[i])
Max=sales[i];
if(Min>sales[i])
Min=sales[i];
}
}
//设置max,min,avg
if(flag)
{
Avg=Sum*1.0/m;
max=Max;
min=Min;
average=Avg;
}
else
{
max=0;
min=0;
average=0;
}
}
SALES::Sales::Sales()
{
m=4;//切记更新
double Max=-999;
double Min=999;
double Avg=0;
double Sum=0;
int i=0;
while(i<4)
{
cout<<"\nPlease enter the number：";
cin>>sales[i];
Sum+=sales[i];
if(Max<sales[i])
Max=sales[i];
if(Min>sales[i])
Min=sales[i];
i++;
}
Avg=Sum*1.0/m;
max=Max;
min=Min;
average=Avg;
}
void SALES::Sales::showSales()
{
cout<<"\nshow on!"<<endl;
cout<<"arr is:";
//SALES::Sales::
showS(m);
cout<<"\n"<<"max="<<max<<"  min="<<min<<"  avg="<<average<<endl;
cout<<"show end!"<<endl;
}

#include <iostream>
#include "SALES.h"
using namespace std;
using namespace SALES;
void main104()
{
double arr[6]={10,5.5,4.5,7.4,5.6,9.7};
Sales s1(arr,4);
s1.showSales();
Sales s2=Sales();
s2.showSales();

system("pause");

}