C++primer plus第六版课后编程题答案11.6

stonwth.h

#ifndef STONEWT_h_
#define STONEWT_h_
#include <iostream>
using namespace std;
enum Mode{STONE,POUNDS};//方便main115,cpp
class Stonewth
{
private:

enum {Lbs_per_stn=14};
Mode mode;
int stone;
double pds_left;
double pounds;
public:
Stonewth(double lbs)
{
mode=POUNDS;//用于控制输出什么格式
stone=int(lbs)/Lbs_per_stn;
pds_left=int(lbs)%Lbs_per_stn+lbs-int(lbs);
pounds=lbs;
};
Stonewth(){
mode=POUNDS;//默认为镑
stone=pds_left=pounds=0;
};
Stonewth(int stn,double lbs)
{
mode=POUNDS;
stone=stn;
pds_left=lbs;
pounds=stn*Lbs_per_stn+lbs;
};
void setMode(Mode form=STONE)
{
if(form==STONE)
mode=STONE;
else if(form==POUNDS)
mode=POUNDS;
else
cout<<"Invail mode !"<<endl;
}
Stonewth operator+(const Stonewth &s)const//这里我就选最简单的了
{
double newpounds=pounds+s.pounds;
return Stonewth(newpounds);
}
Stonewth operator-(const Stonewth &s)const
{
double newpounds=pounds-s.pounds;
return Stonewth(newpounds);
}
Stonewth operator*(double m)const//我这里选择重载常数*
{
double newpounds=pounds*m;
return Stonewth(newpounds);
}
//11.6
bool operator<(const Stonewth &s)
{
return pounds>s.pounds;
}
bool operator>(const Stonewth &s)
{
return s.pounds<pounds;
}

friend ostream& operator<<(ostream &os,const Stonewth &s)
{
if(s.mode==STONE)
os<<s.stone<<" stone!"<<endl;
else if(s.mode==POUNDS)
os<<s.pounds+s.pds_left<<" pounds!"<<endl;
else
os<<"error!"<<endl;
return os;
}

};
#endif

main116.cpp
#include <iostream>
#include "stonewt.h"
using namespace std;
void main116()
{
Stonewth s[6]={10,9.5,19};
//Stonewth s1=10;
//cout<<s1<<endl;
Stonewth temp(11);
for(int i=0;i<3;i++)
cout<<s[i]<<endl;
for(int i=3;i<6;i++)
{
cout<<"enter the pounds:"<<endl;
double in;
cin>>in;
s[i]=in;
}
//没有重载=，懒得重载了，这里会有点问题，自己改下
Stonewth max=-999;
Stonewth min=999;
for(int i=0;i<6;i++)
{
if(max<s[i])
max=s[i];
if(min>s[i])
min=s[i];
if(s[i]>temp)
cout<<s[i]<<endl;
}

cout<<"max="<<max<<" min="<<min<<endl;
cin.get();
cin.get();

}