C++ Primer Plus第六版编程练习11.6解答

stonewt2.h

// stonewt2.h -- definition for the Stonewt class#ifndef STONEWT2_H_#define STONEWT2_H_#include <iostream>class Stonewt{public:    enum Mode {stnFormat, pdsFormat};private:    enum {Lbs_per_stn = 14};      // pounds per stone    int stone;                    // whole stones    double pds_left;              // fractional pounds    double pounds;                // entire weight in pounds    Mode mode;                    // stnFormat or pdsFormatpublic:    Stonewt(double pds, Mode m = stnFormat);          // constructor for double pounds    Stonewt(int stn, double lbs, Mode m = stnFormat); // constructor for stone, lbs    Stonewt();                    // default constructor    ~Stonewt();    void set_stnFormat() {mode = stnFormat;}    void set_pdsFormat() {mode = pdsFormat;}    Stonewt operator+(const Stonewt & s) const;    Stonewt operator-(const Stonewt & s) const;    Stonewt operator*(double n) const;    bool operator>(const Stonewt & s) const;    bool operator<(const Stonewt & s) const;    bool operator==(const Stonewt & s) const;    friend std::ostream & operator<<(std::ostream & os, const Stonewt & s);};#endif

stonewt2.cpp

// stonewt.cpp -- Stonewt methods#include <iostream>using std::cout;#include "stonewt2.h"// construct Stonewt object from double valueStonewt::Stonewt(double pds, Mode m){    stone = int (pds) / Lbs_per_stn;    // integer division    pds_left = int (pds) % Lbs_per_stn + pds - int(pds);    pounds = pds;    mode = m;}// construct Stonewt object from stone, double valuesStonewt::Stonewt(int stn, double lbs, Mode m){    stone = stn;    pds_left = lbs;    pounds =  stn * Lbs_per_stn +lbs;    mode = m;}Stonewt::Stonewt()          // default constructor, wt = 0{    stone = pounds = pds_left = 0;    mode = stnFormat;}Stonewt::~Stonewt()         // destructor{}Stonewt Stonewt::operator+(const Stonewt & s) const{    double pds = pounds + s.pounds;    Stonewt temp(pds);    return temp;}Stonewt Stonewt::operator-(const Stonewt & s) const{    double pds = pounds - s.pounds;    Stonewt temp(pds);    return temp;}Stonewt Stonewt::operator*(double n) const{    double pds = pounds * n;    Stonewt temp(pds);    return temp;}bool Stonewt::operator>(const Stonewt & s) const{    return (pounds > s.pounds);}bool Stonewt::operator<(const Stonewt & s) const{    return (pounds < s.pounds);}bool Stonewt::operator==(const Stonewt & s) const{    return (pounds == s.pounds);}std::ostream & operator<<(std::ostream & os, const Stonewt & s){    if(s.mode==Stonewt::stnFormat)        os << s.stone << " stone, " << s.pds_left << " pounds";    else        os << s.pounds << " pounds";    return os;}

usestonewt2.h

//usestonewt2.cpp -- using the fourth draft of the Time class//compile usetime3.cpp and mytime3.cpp together#include <iostream>#include "stonewt2.h"int main(){    using std::cout;    using std::endl;    using std::cin;    Stonewt stn[6]= {13.9,11,23};    int i;    double pds;    for(i=3; i<6; i++)    {        cout<<"Please enter the number of Stn "<<i<<" :";        cin>>pds;        stn[i]=pds;    }    //show the array of Stonewt    for(i=0; i<6; i++)    {        cout<<"stn "<<i<<" weighs "<<stn[i];        stn[i].set_pdsFormat();        cout<<",\nwhich is "<<stn[i]<<" in whole pounds.\n\n";    }    Stonewt max=stn[0];    Stonewt min=stn[0];    Stonewt tag(11,0);    int count=0;    for(i=0; i<6; i++)    {        if(stn[i]>max)            max=stn[i];        if(stn[i]<min)            min=stn[i];        if(stn[i]>tag||stn[i]==tag)            count++;    }    cout<<"The max of array is stn "<<i<<" ,which weighs "<<max<<endl;    cout<<"The min of array is stn "<<i<<" ,which weighs "<<min<<endl;    cout<<"There are "<<count<<" Stonewt which weighs greater or equal to 11 stone.";    cin.get();    return 0;}