C.Primer.Plus(第六版)第11章 编程练习

//11.1

//vector.h -- Vector class with << mode state#ifndef VECTOR__H__#define VECTOR__H__#include <iostream>namespace VECTOR{    class Vector    {    public:        enum Mode{RECT,POL};        //RECT to rectangular,POL for Polar modes    private:        double x;//horizontal value        double y;// vertical value        double mag;//length of vector        double ang;//direction if vector in degrees        Mode mode;        //private methods for setting values        void set_mag();        void set_ang();        void set_x();        void set_y();    public:        Vector();        Vector(double n1,double n2,Mode form = RECT);        void reset(double n1,double n2,Mode form = RECT);        ~Vector();        double xval() const {return x;}//类定义自动转换为内联函数        double yval() const {return y;}        double magval() const {return mag;}        double angval() const {return ang;}        void polar_mode();//set mode to POL        void rect_mode();//set mode to RECT        //operator overloading        Vector operator+(const Vector & b) const;        Vector operator-(const Vector & b) const;        Vector operator*(double n) const;        Vector operator-() const;        //friends        friend Vector operator*(double n,const Vector & a);        friend std::ostream & operator<<(std::ostream & os,const Vector & v);//返回类型为cout、cerr等标准输出对象    };}//end namespace VECTOR    #endif

//vector.cpp --methods for the Vector class#include <cmath>#include "vector.h"using std::sqrt;using std::sin;using std::cos;using std::atan;using std::atan2;using std::cout;using std::cin;namespace VECTOR{    //computer degrees in one radian    const double Rad_to_deg = 45.0/atan(1.0);    //should be about 57.2957795130823    //private methods    //calcualtes magnitude from x and y    void Vector::set_mag()    {        mag = sqrt(x*x+y*y);    }    void Vector::set_ang()    {        if(x == 0 && y == 0)            ang =0.0;        else            ang = atan2(y,x);    }    void Vector::set_x()    {        x = mag * cos(ang);    }    void Vector::set_y()    {        y = mag * sin(ang);    }    //public methods    Vector::Vector()    {        x = y =mag = ang = 0.0;        mode = RECT;    }    Vector::Vector(double n1,double n2,Mode form)    {        mode = form;        if(form == RECT)        {            x = n1;            y = n2;            set_ang();            set_mag();        }        else if(form == POL)        {            mag = n1;            ang = n2/Rad_to_deg;            set_x();            set_y();        }        else        {            cout<<"Incorrect 3rd argument to Vector()";            cout<<",vector set to 0.\n";            x = y = mag = ang =0.0;            mode = RECT;        }    }    //reset vector from rectangular coordinates if form is    //RECT (the default) or else from polar coordinates if from is POL    void Vector::reset(double n1,double n2,Mode form)    {        mode = form;        if(form == RECT)        {            x = n1;            y = n2;            set_mag();            set_ang();        }        else if(form == POL)        {            mag = n1;            ang = n2/Rad_to_deg;            set_x();            set_y();        }        else        {            cout<<"Incorrect 3rd argument to Vector()";            cout<<",vector set to 0.\n";            x = y = mag = ang =0.0;            mode = RECT;        }    }    Vector::~Vector() //destructor    {    }    void Vector::polar_mode() //set to polar mode    {        mode = POL;    }    void Vector::rect_mode()//set to rectangular mode    {        mode = RECT;    }    //operator overloading    //add two Vectors    Vector Vector::operator+(const Vector & b) const    {        return Vector(x+b.x,y+b.y);    }    Vector Vector::operator-(const Vector & b) const    {        return Vector(x-b.x,y-b.y);    }    //reverse sign of Vector    Vector Vector::operator-() const    {        return Vector(-x,-y);    }    //multiply vector by n    Vector Vector::operator*(double n) const    {        return Vector(n*x,n*y);    }    //friend methods    //multiply n by Vector a    Vector operator*(double n,const Vector & a)    {        return a*n;    }    //display rectangular coordinates if mode is RECT,    //else display polar coordinates if mode is POL    std::ostream & operator<<(std::ostream & os, const Vector & v)    {        if(v.mode == Vector::RECT)        {            os<<"(x,y) =("<<v.x<<","<<v.y<<")";        }        else if(v.mode == Vector::POL)        {            os<<"(m,a) = ("<<v.mag<<" ,"                <<v.ang * Rad_to_deg<<")";        }        else            os<<"Vector object mode is invalid.";        return os;    }}//end namespace VECTOR

//randwalk.cpp -- using the Vector class#include <iostream>#include "vector.h"#include <cstdlib>#include <ctime>#include <fstream>//int main(){    using namespace std;    using VECTOR::Vector;    srand(time(0));    double direction;    Vector step;    Vector result(0.0,0.0);    unsigned long steps = 0;    double target;    double dstep;    ofstream fout;//    fout.open("test.txt");//    cout<<"Enter target distanee(q to quit):";    while(cin>>target)    {        cout<<"Enter step length:";        if(!(cin>>dstep))            break;        fout<<"Target Distance: "<<target<<" , Step Size: "<<dstep<<endl;//        while(result.magval()<target)        {            fout<<steps<<":"<<result<<endl;//            direction = rand() % 360;            step.reset(dstep,direction,Vector::POL);            result = result + step;            steps++;        }        fout<<steps<<":"<<result<<endl;//        cout<<"After "<<steps<<" steps,the subject "            "has the folling location:\n";        fout<<"After "<<steps<<" steps,the subject "            "has the folling location:\n";//        cout<<result<<endl;        fout<<result<<endl;        result.polar_mode();        cout<<" or \n"<<result<<endl;        fout<<" or \n"<<result<<endl;        cout<<"Average outward distance per step = "            <<result.magval()/steps<<endl;        fout<<"Average outward distance per step = "            <<result.magval()/steps<<endl;    }    cout<<"Bye!\n";    cin.clear();    cin.sync();    return 0 ;}

//11.2

//vector.h -- Vector class with << mode state#ifndef VECTOR__H__#define VECTOR__H__#include <iostream>namespace VECTOR{    class Vector    {    public:        enum Mode{RECT,POL};        //RECT to rectangular,POL for Polar modes    private:        double x;//horizontal value        double y;// vertical value        double mag;//length of vector        double ang;//direction if vector in degrees        Mode mode;        //private methods for setting values        //void set_mag();        //void set_ang();        double set_mag();        double set_ang();        void set_x();        void set_y();    public:        Vector();        Vector(double n1,double n2,Mode form = RECT);        void reset(double n1,double n2,Mode form = RECT);        ~Vector();        double xval() const {return x;}//类定义自动转换为内联函数        double yval() const {return y;}        //double magval() const {return mag;}        //double angval() const {return ang;}        double magval();        double angval();         void polar_mode();//set mode to POL        void rect_mode();//set mode to RECT        //operator overloading        Vector operator+(const Vector & b) const;        Vector operator-(const Vector & b) const;        Vector operator*(double n) const;        Vector operator-() const;        //friends        friend Vector operator*(double n,const Vector & a);        friend std::ostream & operator<<(std::ostream & os,const Vector & v);//返回类型为cout、cerr等标准输出对象    };}//end namespace VECTOR    #endif

//vector.cpp --methods for the Vector class#include <cmath>#include "vector.h"using std::sqrt;using std::sin;using std::cos;using std::atan;using std::atan2;using std::cout;using std::cin;namespace VECTOR{    //computer degrees in one radian    const double Rad_to_deg = 45.0/atan(1.0);    //should be about 57.2957795130823    //private methods    //calcualtes magnitude from x and y    /*    void Vector::set_mag()    {        mag = sqrt(x*x+y*y);    }    void Vector::set_ang()    {        if(x == 0 && y == 0)            ang =0.0;        else            ang = atan2(y,x);    }    void Vector::set_x()    {        x = mag * cos(ang);    }    */    double Vector::set_mag()    {        mag = sqrt(x*x+y*y);        return mag;    }    double Vector::set_ang()    {        if(x == 0 && y == 0)            ang =0.0;        else            ang = atan2(y,x);        return ang;    }    double Vector::magval()     {        return set_mag();    }    double Vector::angval()    {        return set_ang();    }     void Vector::set_x()    {        x = mag * cos(ang);    }    void Vector::set_y()    {        y = mag * sin(ang);    }    //public methods    Vector::Vector()    {        x = y =mag = ang = 0.0;        mode = RECT;    }    Vector::Vector(double n1,double n2,Mode form)    {        mode = form;        if(form == RECT)        {            x = n1;            y = n2;            magval();            angval();        }        else if(form == POL)        {            mag = n1;            ang = n2/Rad_to_deg;            set_x();            set_y();        }        else        {            cout<<"Incorrect 3rd argument to Vector()";            cout<<",vector set to 0.\n";            x = y = mag = ang =0.0;            mode = RECT;        }    }    //reset vector from rectangular coordinates if form is    //RECT (the default) or else from polar coordinates if from is POL    void Vector::reset(double n1,double n2,Mode form)    {        mode = form;        if(form == RECT)        {            x = n1;            y = n2;            magval();            angval();        }        else if(form == POL)        {            mag = n1;            ang = n2/Rad_to_deg;            set_x();            set_y();        }        else        {            cout<<"Incorrect 3rd argument to Vector()";            cout<<",vector set to 0.\n";            x = y = mag = ang =0.0;            mode = RECT;        }    }    Vector::~Vector() //destructor    {    }    void Vector::polar_mode() //set to polar mode    {        mode = POL;    }    void Vector::rect_mode()//set to rectangular mode    {        mode = RECT;    }    //operator overloading    //add two Vectors    Vector Vector::operator+(const Vector & b) const    {        return Vector(x+b.x,y+b.y);    }    Vector Vector::operator-(const Vector & b) const    {        return Vector(x-b.x,y-b.y);    }    //reverse sign of Vector    Vector Vector::operator-() const    {        return Vector(-x,-y);    }    //multiply vector by n    Vector Vector::operator*(double n) const    {        return Vector(n*x,n*y);    }    //friend methods    //multiply n by Vector a    Vector operator*(double n,const Vector & a)    {        return a*n;    }    //display rectangular coordinates if mode is RECT,    //else display polar coordinates if mode is POL    std::ostream & operator<<(std::ostream & os, const Vector & v)    {        if(v.mode == Vector::RECT)        {            os<<"(x,y) =("<<v.x<<","<<v.y<<")";        }        else if(v.mode == Vector::POL)        {            os<<"(m,a) = ("<<v.mag<<" ,"                <<v.ang * Rad_to_deg<<")";        }        else            os<<"Vector object mode is invalid.";        return os;    }}//end namespace VECTOR

//randwalk.cpp -- using the Vector class#include <iostream>#include "vector.h"#include <cstdlib>#include <ctime>int main(){    using namespace std;    using VECTOR::Vector;    srand(time(0));    double direction;    Vector step;    Vector result(0.0,0.0);    unsigned long steps = 0;    double target;    double dstep;    cout<<"Enter target distanee(q to quit):";    while(cin>>target)    {        cout<<"Enter step length:";        if(!(cin>>dstep))            break;        while(result.magval()<target)        {            direction = rand() % 360;            step.reset(dstep,direction,Vector::POL);            result = result + step;            steps++;        }        cout<<"After "<<steps<<" steps,the subject "            "has the folling location:\n";        cout<<result<<endl;        result.polar_mode();        cout<<" or \n"<<result<<endl;        cout<<"Average outward distance per step = "            <<result.magval()/steps<<endl;    }    cout<<"Bye!\n";    cin.clear();    cin.sync();    return 0 ;}

//11.3

//vector.h -- Vector class with << mode state#ifndef VECTOR__H__#define VECTOR__H__#include <iostream>namespace VECTOR{    class Vector    {    public:        enum Mode{RECT,POL};        //RECT to rectangular,POL for Polar modes    private:        double x;//horizontal value        double y;// vertical value        double mag;//length of vector        double ang;//direction if vector in degrees        Mode mode;        //private methods for setting values        void set_mag();        void set_ang();        void set_x();        void set_y();    public:        Vector();        Vector(double n1,double n2,Mode form = RECT);        void reset(double n1,double n2,Mode form = RECT);        ~Vector();        double xval() const {return x;}//类定义自动转换为内联函数        double yval() const {return y;}        double magval() const {return mag;}        double angval() const {return ang;}        void polar_mode();//set mode to POL        void rect_mode();//set mode to RECT        //operator overloading        Vector operator+(const Vector & b) const;        Vector operator-(const Vector & b) const;        Vector operator*(double n) const;        Vector operator-() const;        //friends        friend Vector operator*(double n,const Vector & a);        friend std::ostream & operator<<(std::ostream & os,const Vector & v);//返回类型为cout、cerr等标准输出对象    };}//end namespace VECTOR    #endif

//vector.cpp --methods for the Vector class#include <cmath>#include "vector.h"using std::sqrt;using std::sin;using std::cos;using std::atan;using std::atan2;using std::cout;using std::cin;namespace VECTOR{    //computer degrees in one radian    const double Rad_to_deg = 45.0/atan(1.0);    //should be about 57.2957795130823    //private methods    //calcualtes magnitude from x and y    void Vector::set_mag()    {        mag = sqrt(x*x+y*y);    }    void Vector::set_ang()    {        if(x == 0 && y == 0)            ang =0.0;        else            ang = atan2(y,x);    }    void Vector::set_x()    {        x = mag * cos(ang);    }    void Vector::set_y()    {        y = mag * sin(ang);    }    //public methods    Vector::Vector()    {        x = y =mag = ang = 0.0;        mode = RECT;    }    Vector::Vector(double n1,double n2,Mode form)    {        mode = form;        if(form == RECT)        {            x = n1;            y = n2;            set_ang();            set_mag();        }        else if(form == POL)        {            mag = n1;            ang = n2/Rad_to_deg;            set_x();            set_y();        }        else        {            cout<<"Incorrect 3rd argument to Vector()";            cout<<",vector set to 0.\n";            x = y = mag = ang =0.0;            mode = RECT;        }    }    //reset vector from rectangular coordinates if form is    //RECT (the default) or else from polar coordinates if from is POL    void Vector::reset(double n1,double n2,Mode form)    {        mode = form;        if(form == RECT)        {            x = n1;            y = n2;            set_mag();            set_ang();        }        else if(form == POL)        {            mag = n1;            ang = n2/Rad_to_deg;            set_x();            set_y();        }        else        {            cout<<"Incorrect 3rd argument to Vector()";            cout<<",vector set to 0.\n";            x = y = mag = ang =0.0;            mode = RECT;        }    }    Vector::~Vector() //destructor    {    }    void Vector::polar_mode() //set to polar mode    {        mode = POL;    }    void Vector::rect_mode()//set to rectangular mode    {        mode = RECT;    }    //operator overloading    //add two Vectors    Vector Vector::operator+(const Vector & b) const    {        return Vector(x+b.x,y+b.y);    }    Vector Vector::operator-(const Vector & b) const    {        return Vector(x-b.x,y-b.y);    }    //reverse sign of Vector    Vector Vector::operator-() const    {        return Vector(-x,-y);    }    //multiply vector by n    Vector Vector::operator*(double n) const    {        return Vector(n*x,n*y);    }    //friend methods    //multiply n by Vector a    Vector operator*(double n,const Vector & a)    {        return a*n;    }    //display rectangular coordinates if mode is RECT,    //else display polar coordinates if mode is POL    std::ostream & operator<<(std::ostream & os, const Vector & v)    {        if(v.mode == Vector::RECT)        {            os<<"(x,y) =("<<v.x<<","<<v.y<<")";        }        else if(v.mode == Vector::POL)        {            os<<"(m,a) = ("<<v.mag<<" ,"                <<v.ang * Rad_to_deg<<")";        }        else            os<<"Vector object mode is invalid.";        return os;    }}//end namespace VECTOR

//randwalk.cpp -- using the Vector class#include <iostream>#include "vector.h"#include <cstdlib>#include <ctime>#include <fstream>//int main(){    using namespace std;    using VECTOR::Vector;    srand(time(0));    double direction;    Vector step;    Vector result(0.0,0.0);    unsigned long steps = 0;    double target;    double dstep;    int testsize;    double maxtep = 0;    double mintep = 0;    static double avertep = 0;    ofstream fout;//    fout.open("test.txt");//    cout<<"Enter testsize(q to quit):";    while(!(cin>>testsize))    {        cout<<"Enter the true genre(q to quit):";        cin.clear();        cin.sync();    }    int n = testsize;    while(n--)    {        cout<<"Enter target distanee(q to quit):";        while(!(cin>>target))            {                cout<<"Enter the true genre(q to quit):";                cin.clear();                cin.sync();            }        cout<<"Enter step length:";        while(!(cin>>dstep))            {                cout<<"Enter the true genre(q to quit):";                cin.clear();                cin.sync();            }        while(result.magval()<target)        {            direction = rand() % 360;            step.reset(dstep,direction,Vector::POL);            result = result + step;            steps++;        }        cout<<"After "<<steps<<" steps,the subject "            "has the folling location:\n";        if(avertep == 0)            mintep = steps;        if(steps>maxtep)            maxtep = steps;        if(steps<mintep)            mintep = steps;        avertep += steps;    }    cout<<"In total "<<testsize<<" mesurement,the maxtep is "<<maxtep<<" ,the mintep is "<<mintep<<" and the avertep is "<<(avertep/testsize)<<endl;    return 0 ;}

//11.4

//sale.h#include <iostream>#ifndef __SALE__H__#define __SALE__H__namespace SALES{    class Sales    {    private:        static const int QUARTERS = 4;        double sales[QUARTERS];        double average;        double max;        double min;    public:        Sales(const double ar[],int n);        Sales();        void showSales() const;    };}#endif

//sale.cpp#include <iostream>#include "sale.h"using std::cin;using std::cout;using std::endl;using std::string;namespace SALES{    static double calcAverage(double arr[], int arrsize)    {        double sum = 0;        for(int i = 0;i<arrsize;i++)            sum+=arr[i];        return (sum/arrsize);    }    static double calcMax(double arr[], int arrsize)    {        int idMax = 0;        for(int i =1;i<arrsize;i++)        {            if(arr[i]>arr[idMax])                idMax = i;        }        return arr[idMax];    }    static double calcMin(double arr[], int arrsize)    {        int idMin = 0;        for(int i =1;i<arrsize;i++)        {            if(arr[i]<arr[idMin])                idMin = i;        }        return arr[idMin];    }Sales::Sales(const double ar[],int n)    {        int times = n<QUARTERS?n:QUARTERS;        for(int i = 0;i<times;i++)            (*this).sales[i]=ar[i];        for(int i =times;i<QUARTERS;i++)            this->sales[i] = 0;        this->average = calcAverage(this->sales, times);          this->max = calcMax(this->sales, times);          this->min = calcMin(this->sales, times);     }Sales::Sales()    {        cout << "Please enter " << QUARTERS << " sale record：";          int times = QUARTERS;          double  arr[QUARTERS] = {0};          for (int i = 0;i < QUARTERS; i++) {              cin >> arr[i];              if (!cin) {                  times = i;  //表示输入异常                break;              }          }          *this = Sales::Sales(arr, QUARTERS);  //先得到初始数据在进行操作        this->average = calcAverage(this->sales, times);          this->max = calcMax(this->sales, times);         this->min = calcMin(this->sales, times);      }    void Sales::showSales() const    {        cout << "sales: ";          for(int i = 0;i<QUARTERS;i++)             cout<<this->sales[i]<<" ";        cout << endl;          cout << "average: " <<this->average << endl;          cout << "max: " << this->max << endl;          cout << "min: " << this->min << endl;      }}

//main.cpp#include <iostream>  #include "sale.h" using namespace std;int main ()   {           using namespace SALES;       const double salesList[] = {2.24,234,53,23.6,6.4};      Sales salesCar(salesList, (sizeof(salesList)/sizeof(salesList[0])));  ;     salesCar.showSales();      Sales salesBus;     salesBus.showSales();      }   

//11.5

//stonewt.h -- definition for the Stonewt class#ifndef STONEWT__H__#define STONEWT__H__class Stonewt{public:    enum Sort{POUNDS,FRAC_POUND};private:    static const int Lbs_per_stn = 14;    int stone;  //whole stones    double pds_left;//fractional pounds    double pounds;//entire weight in pounds    Sort sort;public:    Stonewt(int stn,double lbs,Sort form);    Stonewt();    ~Stonewt();    friend Stonewt operator+(Stonewt & s1,Stonewt & s2);    friend Stonewt operator-(Stonewt & s1,Stonewt & s2);    friend Stonewt operator*(Stonewt & s1,Stonewt & s2);    friend std::ostream & operator<<(std::ostream & os, const Stonewt & s1);};#endif

//stonewt.cpp#include <iostream>using std::cout;#include "stonewt.h"Stonewt::Stonewt(int stn,double lbs,Sort form){    if(form == POUNDS)    {        stone = int(lbs)/Lbs_per_stn + stn;        pds_left = int(lbs) % Lbs_per_stn + lbs -int(lbs);        pounds = lbs+ stn * Lbs_per_stn;        sort = form;    }    else if(form == FRAC_POUND)    {        stone = int(lbs)/Lbs_per_stn + stn;        pds_left = int(lbs) % Lbs_per_stn + lbs -int(lbs);        pounds = lbs+ stn * Lbs_per_stn;        sort = form;    }    else    {        cout<<"data form don't matching.";        stone = pds_left = pounds = 0;        form = FRAC_POUND;    }}Stonewt::Stonewt(){    stone = pounds = pds_left = 0;    sort = FRAC_POUND;}Stonewt::~Stonewt(){}Stonewt operator+(Stonewt & s1,Stonewt & s2){    Stonewt s;    s.pounds = s1.pounds + s2.pounds;    s.stone = s.pounds/Stonewt::Lbs_per_stn;    s.pds_left = int(s.pounds) % Stonewt::Lbs_per_stn + s.pounds - int(s.pounds);    return s;}Stonewt operator-(Stonewt & s1,Stonewt & s2){    Stonewt s;    s.pounds = s1.pounds - s2.pounds;    s.stone = s.pounds/Stonewt::Lbs_per_stn;    s.pds_left = int(s.pounds) % Stonewt::Lbs_per_stn + s.pounds - int(s.pounds);    return s;}Stonewt operator*(Stonewt & s1,Stonewt & s2){    Stonewt s;    s.pounds = s1.pounds * s2.pounds;    s.stone = s.pounds/Stonewt::Lbs_per_stn;    s.pds_left = int(s.pounds) % Stonewt::Lbs_per_stn + s.pounds - int(s.pounds);    return s;}std::ostream & operator<<(std::ostream & os, const Stonewt & s1){    if(s1.sort == Stonewt::FRAC_POUND)        os<<"The stone is "<<s1.stone<<" and the pounds is "<<s1.pds_left<<std::endl;    else        os<<"The pounds is "<<s1.pounds<<std::endl;    return os;}

//main.cpp -- user-defined conversion#include <iostream>#include "stonewt.h"using std::cout;using std::cin;using std::endl;int main(){    Stonewt stone_one(120,102.2,Stonewt::FRAC_POUND);    Stonewt stone_two(22,187.8,Stonewt::POUNDS);    cout<<stone_one;    cout<<stone_two;    Stonewt stone_three = stone_one + stone_two;    cout<<stone_three;    stone_three = stone_one - stone_two;    cout<<stone_three;    stone_three = stone_one * stone_two;    cout<<stone_three;}

//11.6

//stonewt.h -- definition for the Stonewt class#ifndef STONEWT__H__#define STONEWT__H__class Stonewt{private:    static const int Lbs_per_stn = 14;    int stone;  //whole stones    double pds_left;//fractional pounds    double pounds;//entire weight in poundspublic:    Stonewt(int stn,double lbs);    Stonewt(double _pounds);    Stonewt();    ~Stonewt();    friend bool operator<(Stonewt & s1,Stonewt & s2);    friend bool operator<=(Stonewt & s1,Stonewt & s2);    friend bool operator>(Stonewt & s1,Stonewt & s2);    friend bool operator>=(Stonewt & s1,Stonewt & s2);    friend bool operator==(Stonewt & s1,Stonewt & s2);    friend bool operator!=(Stonewt & s1,Stonewt & s2);    friend std::ostream & operator<<(std::ostream & os, const Stonewt & s1);};#endif

//stonewt.cpp#include <iostream>using std::cout;#include "stonewt.h"Stonewt::Stonewt(int stn,double lbs){    stone = int(lbs)/Lbs_per_stn + stn;    pds_left = int(lbs) % Lbs_per_stn + lbs -int(lbs);    pounds = lbs+ stn * Lbs_per_stn;}Stonewt::Stonewt(){    stone = pounds = pds_left = 0;}Stonewt::Stonewt(double _pounds){    stone = pds_left = 0;     pounds = _pounds;}Stonewt::~Stonewt(){}bool operator>(Stonewt & s1,Stonewt & s2){    return s1.pounds > s2.pounds;}bool operator>=(Stonewt & s1,Stonewt & s2){    return s1.pounds >= s2.pounds;}bool operator<(Stonewt & s1,Stonewt & s2){    return s1.pounds < s2.pounds;}std::ostream & operator<<(std::ostream & os, const Stonewt & s1){    os<<s1.pounds;    return os;}bool operator<=(Stonewt & s1,Stonewt & s2){    return s1.pounds <= s2.pounds;}bool operator==(Stonewt & s1,Stonewt & s2){    return s1.pounds == s2.pounds;}bool operator!=(Stonewt & s1,Stonewt & s2){    return s1.pounds != s2.pounds;}

//main.cpp -- user-defined conversion#include <iostream>#include "stonewt.h"using std::cout;using std::cin;using std::endl;int main(){    const int N = 6;    Stonewt stonewt[N]= {        Stonewt(12),Stonewt(4),Stonewt(7),    };    for(int i = 3;i<6;i++)    {        cout<<"Please enter the Initialization data:";        double s_stone;        cin>>s_stone;        cin.get();        stonewt[i] = Stonewt(s_stone);    }    Stonewt s_example(11);    static int max = 0;    static int min = 0;    static int count = 0;    for(int i=0;i<N-1;i++)    {        max = stonewt[max]>stonewt[i+1]?max:i+1;        min = stonewt[min]<stonewt[i+1]?min:i+1;    }    for(int i=0;i<N;i++)    {        if(stonewt[i]>=s_example)            count++;    }    cout<<"The max element is "<<stonewt[max]<<", the min element is "<<stonewt[min]<<" and the number of elements greater than 11 is:"<<count<<endl;}

//11.7

//comlpex0.h#ifndef COMPLEX0__H__#define COMPLEX0__H__#include <iostream>class Complex{private:    double real;    double imaginary;public:    Complex();    Complex(double _real,double _imaginary);    Complex operator+(const Complex & c1);    Complex operator-(const Complex & c1);    Complex operator*(const Complex & c1);    Complex operator*(double x);    friend Complex operator*(double x,Complex & c1){return c1 * x;}    Complex operator~();    friend std::istream & operator>>(std::istream & is,Complex & c1);    friend std::ostream & operator<<(std::ostream & os,const Complex & c1);};#endif

//complex0.cpp#include "complex0.h"Complex::Complex(){    real = imaginary = 0;}Complex::Complex(double _real,double _imaginary){    real = _real;    imaginary = _imaginary;}Complex Complex::operator+(const Complex & c1){    Complex c;    c.real = real + c1.real;    c.imaginary = imaginary + c1.imaginary;    return c;}Complex Complex::operator-(const Complex & c1){    Complex c;    c.real = real - c1.real;    c.imaginary = imaginary - c1.imaginary;    return c;}Complex Complex::operator*(const Complex & c1){    Complex c;    c.real = real * c1.real - imaginary * c1.imaginary;    c.imaginary = real * c1.imaginary + imaginary * c1.real;    return c;}Complex Complex::operator*(double x){    Complex c;    c.real = real * x;    c.imaginary = imaginary * x;    return c;}Complex Complex::operator~(){    Complex c;    c.imaginary = - (*this).imaginary;    c.real = (*this).real;    return c;}std::istream & operator>>(std::istream & is,Complex & c1){    std::cout<<"real: ";    if(is >> c1.real)    {        std::cout<<"imaginary: ";        is >> c1.imaginary;    }    return is;}std::ostream & operator<<(std::ostream & os,const Complex & c1){    os<<"("<<c1.real<<","<<c1.imaginary<<"i)"<<std::endl;    return os;}

//main.cpp#include <iostream>#include "complex0.h"using namespace std;int main(){    Complex a(3.0,4.0);    Complex c;    cout<<"Enter a complex number(q to quit):\n";    while(cin>>c)    {        cout<<"c is "<<c<<endl;        cout<<"complex conjugate is "<<~c<<'\n';        cout<<"a is"<<a<<endl;        cout<<"a + c is "<<a + c<<endl;        cout<<"a - c is "<<a - c<<endl;        cout<<"a * c is "<<a * c<<endl;        cout<<"2 * c is "<<2 * c<<endl;        cout<<"c * 2 is "<<c * 2<<endl;        cout<<"Enter a complex number (q to quit):\n";    }    cout<<"Done!\n";    return 0;}