C++ Primer Plus 第六版第十五章课后编程练习答案

- 日理万妓 2023-07-24 14:39 41阅读 0赞

tv.h

//改自清单15.1
    #ifndef TV_H_
    #define TV_H_
    class Remote;
    
    class Tv
    {
        friend class Remote;
    public:
        enum { Off, On };
        enum { MinVal, MaxVal = 20 };
        enum { Antenna, Cable };
        enum { TV, DVD };
    
        Tv(int s = Off, int mc = 125) : state(s), volume(5), maxchannel(mc), channel(2), mode(Cable), input(TV) {}
        void onoff() { state = (state == On) ? Off : On; }
        bool ison() const { return state == On; }
        bool volup();
        bool voldown();
        void chanup();
        void chandown();
        void set_mode() { mode = (mode == Antenna) ? Cable : Antenna; }
        void set_input() { input = (input == TV) ? DVD : TV; }
        void settings() const;
        void change_r_mode(Remote & r);
    private:
        int state;
        int volume;
        int maxchannel;
        int channel;
        int mode;
        int input;
    };
    
    class Remote
    {
        friend class Tv;
    private:
        int mode;
        int r_mode;
        enum { Regular, Interact};
    public:
        Remote(int m = Tv::TV, int f = Regular) : mode(m), r_mode(f) {}
        bool volup(Tv & t) { return t.volup(); }
        bool voldown(Tv & t) { return t.voldown(); }
        void onoff(Tv & t) { t.onoff(); }
        void chanup(Tv & t) { t.chanup(); }
        void chandown(Tv & t) { t.chandown(); }
        void set_chan(Tv & t, int c) { t.channel = c; }
        void set_mode(Tv & t) { t.set_mode(); }
        void set_input(Tv & t) { t.set_input(); }
        void show_r_mode() const { std::cout << "Now the remote mode is " << (r_mode == Regular ? "Regular" : "Interact") << ".\n";}
    };
    
    inline void Tv::change_r_mode(Remote & r)
    {
        if (ison())
        {
            if (r.r_mode == Remote::Regular)
                r.r_mode = Remote::Interact;
            else
                r.r_mode = Remote::Regular;
            r.show_r_mode();
        }
        else
        {
            std::cout << "The tv is off, please turn it on!\n";
        }
    }
    
    #endif

tv.cpp

// 清单15.2
    #include <iostream>
    #include "tv.h"
    
    bool Tv::volup()
    {
        if (volume < MaxVal)
        {
            volume++;
            return true;
        }
        else
            return false;
    }
    
    bool Tv::voldown()
    {
        if (volume > MinVal)
        {
            volume--;
            return true;
        }
        else
            return false;
    }
    
    void Tv::chanup()
    {
        if (channel < maxchannel)
            channel++;
        else
            channel = 1;
    }
    
    void Tv::chandown()
    {
        if (channel > 1)
            channel--;
        else
            channel = maxchannel;
    }
    
    void Tv::settings() const
    {
        using std::cout;
        using std::endl;
        cout << "TV is " << (state == Off ? "Off" : "On") << endl;
        if (state == On)
        {
            cout << "Volume setting = " << volume << endl;
            cout << "Channel setting = " << channel << endl;
            cout << "Mode = " << (mode == Antenna ? "antenna" : "cable") << endl;
            cout << "Input = " << (input == TV ? "TV" : "DVD") << endl;
        }
    }

play.cpp

//改自清单15.3
    #include <iostream>
    #include "tv.h"
    
    int main()
    {
        using std::cout;
        Tv s42;
        Remote grey;
        cout << "Initial settings for 42\" TV:\n";
        s42.settings();
        grey.show_r_mode();
        s42.change_r_mode(grey);
        s42.onoff();
        s42.chanup();
        cout << "\nAdjusted settings for 42\" TV:\n";
        s42.chanup();
        cout << "\nAdjusted settings for 42\" TV:\n";
        s42.settings();
    
        s42.change_r_mode(grey);
    
        grey.set_chan(s42, 10);
        grey.volup(s42);
        grey.volup(s42);
        cout << "\n42\" settings after using remote:\n";
        s42.settings();
    
        s42.change_r_mode(grey);
    
        Tv s58(Tv::On);
        s58.set_mode();
        grey.set_chan(s58, 28);
        cout << "\n58\" settings:\n";
        s58.settings();
        grey.show_r_mode();
        s58.change_r_mode(grey);
    
        return 0;
    }

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mean.h

#ifndef MEAN_H
    #define MEAN_H
    #include <stdexcept>
    #include <string>
    
    class bad_hmean : public logic_error
    {
        double v1;
        double v2;
        string name;
    public:
        explicit bad_hmean(const string &n = "hmean", const string &s = "Error in hmean()\n",
                           double a = 0, double b = 0);
        void mesg();
        const char * what() { return "bad arguments in hmean()\n";}
        virtual ~bad_hmean() throw() {}
    };
    
    bad_hmean::bad_hmean(const string &n, const string &s, double a, double b)
            : name(n), logic_error(s), v1(a), v2(b)
    {}
    
    inline void bad_hmean::mesg()
    {
        cout << "hmean(" << v1 << ", " << v2 << "): " << "invalid arguments: a = -b\n";
    }
    
    class bad_gmean : public logic_error
    {
        string name;
    public:
        double v1;
        double v2;
        explicit bad_gmean(const string &n = "gmean", const string &s = "Error in gmean()\n",
                           double a = 0, double b = 0);
        const char * mesg();
        const char * what() { return "bad arguments in gmean()\n";}
        virtual ~bad_gmean() throw() {}
    };
    
    bad_gmean::bad_gmean(const string &n, const string &s, double a, double b)
            : name(n), logic_error(s), v1(a), v2(b)
    {}
    
    inline const char * bad_gmean::mesg()
    {
        return "gmean() arguments should be >=0\n";
    }
    
    #endif

mean.cpp

//改自清单15.10、15.11
    #include <iostream>
    using namespace std;
    #include <string>
    #include "mean.h"
    #include <cmath>
    
    double hmean(double a, double b);
    double gmean(double a, double b);
    int main()
    {
        double x, y, z;
        cout << "Enter two numbers: ";
        while (cin >> x >> y)
        {
            try{
                z = hmean(x, y);
                cout << "Harmonic mean of " << x << " and " << y
                     << " is " << z << endl;
                cout << "Geometric mean of " << x << " and " << y
                     << " is " << gmean(x, y) << endl;
                cout << "Enter next set of numbers <q to quit>: ";
            }
            catch(bad_hmean &bg)
            {
                cout << bg.what();
                cout << "Error message:\n";
                bg.mesg();
                cout << "Try again.\n";
                continue;
            }
            catch (bad_gmean &hg)
            {
                cout << hg.what();
                cout << "Error message:\n";
                cout << hg.mesg();
                cout << "Values used: " << hg.v1 << ", " << hg.v2 << endl;
                cout << "Sorry, you don't get to play any more.\n";
                break;
            }
        }
    
        cout << "Bye!\n";
        return 0;
    }
    
    double hmean(double a, double b)
    {
        if(a == -b)
            throw bad_hmean("hmean", "Error in hmean()\n", a, b);
        return 2.0 * a * b / (a + b);
    }
    
    double gmean(double a, double b)
    {
        if(a < 0 || b < 0)
            throw bad_gmean("gmean", "Error in gmean()\n", a, b);
        return sqrt(a * b);
    }

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mean.h

#ifndef MEAN_H
    #define MEAN_H
    #include <stdexcept>
    #include <string>
    
    class bad : public logic_error
    {
    public:
        double v1;
        double v2;
        string name;
        explicit bad(const string &n, const string &s, double a = 0, double b = 0);
        void mesg();
        virtual ~bad() throw() {}
    };
    
    bad::bad(const string &n, const string &s, double a, double b)
            : name(n), logic_error(s), v1(a), v2(b)
    {}
    
    inline void bad::mesg()
    {
        cout << "Error happened!\n";
    }
    
    class bad_hmean : public bad
    {
    public:
        explicit bad_hmean(const string &n = "hmean", const string &s = "Error in hmean()\n",
                           double a = 0, double b = 0);
        void mesg();
        const char * what() { return "bad arguments in hmean()\n";}
        virtual ~bad_hmean() throw() {}
    };
    
    bad_hmean::bad_hmean(const string &n, const string &s, double a, double b)
            : bad(n, s, a, b)
    {}
    
    inline void bad_hmean::mesg()
    {
        cout << "hmean(" << v1 << ", " << v2 << "): " << "invalid arguments: a = -b\n";
    }
    
    class bad_gmean : public bad
    {
    public:
        explicit bad_gmean(const string &n = "gmean", const string &s = "Error in gmean()\n",
                           double a = 0, double b = 0);
        const char * mesg();
        const char * what() { return "bad arguments in gmean()\n";}
        virtual ~bad_gmean() throw() {}
    };
    
    bad_gmean::bad_gmean(const string &n, const string &s, double a, double b)
            : bad(n, s, a, b)
    {}
    
    inline const char * bad_gmean::mesg()
    {
        return "gmean() arguments should be >=0\n";
    }
    
    #endif

mean.cpp

//改自清单15.10、15.11
    #include <iostream>
    using namespace std;
    #include <string>
    #include "mean.h"
    #include <cmath>
    
    double hmean(double a, double b);
    double gmean(double a, double b);
    int main()
    {
        double x, y, z;
        cout << "Enter two numbers: ";
        while (cin >> x >> y)
        {
            try{
                z = hmean(x, y);
                cout << "Harmonic mean of " << x << " and " << y
                     << " is " << z << endl;
                cout << "Geometric mean of " << x << " and " << y
                     << " is " << gmean(x, y) << endl;
                cout << "Enter next set of numbers <q to quit>: ";
            }
            catch (bad &b)
            {
                b.mesg();
                if(b.name == "hmean")
                {
                    cout << ((bad_hmean &)b).what();
                    cout << "Error message: ";
                    ((bad_hmean &)b).mesg();
                    cout << "Sorry, you don't get to play any more.\n";
                    break;
                }
                else if (b.name == "gmean")
                {
                    cout << ((bad_gmean &)b).what();
                    cout << "Error message: ";
                    cout << ((bad_gmean &)b).mesg();
                    cout << "Values used: " << ((bad_gmean &)b).v1 << ", " <<
                    ((bad_gmean &)b).v2 << endl;
                    cout << "Sorry, you don't get to play any more.\n";
                    break;
                }
                else
                {
                    cout << "Input error.\nTerminated.\n";
                    exit(EXIT_FAILURE);
                }
            }
        }
    
        cout << "Bye!\n";
        return 0;
    }
    
    double hmean(double a, double b)
    {
        if(a == -b)
            throw bad_hmean("hmean", "Error in hmean()\n", a, b);
        return 2.0 * a * b / (a + b);
    }
    
    double gmean(double a, double b)
    {
        if(a < 0 || b < 0)
            throw bad_gmean("gmean", "Error in gmean()\n", a, b);
        return sqrt(a * b);
    }

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sales.h

//清单15.14
    #include <iostream>
    #include <stdexcept>
    #include <string>
    
    class Sales
    {
    public:
        enum { MONTHS = 12 };;
        class bad_index : public std::logic_error
        {
        private:
            int bi;
        public:
            explicit bad_index(int ix, const std::string & s = "Index error in Sales object\n");
            int bi_val() const { return bi; }
            virtual ~bad_index() throw() {}
        };
        explicit Sales(int yy = 0);
        Sales(int yy, const double * gr, int n);
        virtual ~Sales() {}
        int Year() const { return year; }
        virtual double operator[](int i) const;
        virtual double & operator[](int i);
    private:
        double gross[MONTHS];
        int year;
    };
    
    class LabeledSales : public Sales
    {
    public:
        class nbad_index : public Sales::bad_index
        {
        private:
            std::string lbl;
        public:
            nbad_index(const std::string & lb, int ix, const std::string & s = "Index error in LabeledSales object\n");
            const std::string & label_val() const { return lbl; }
            virtual ~nbad_index() throw() {}
        };
        explicit LabeledSales(const std::string & lb = "none", int yy = 0);
        LabeledSales(const std::string & lb, int yy, const double * gr, int n);
        virtual ~LabeledSales() {}
        const std::string & Label() const { return label; }
        virtual double operator[](int i) const;
        virtual double & operator[](int i);
    private:
        std::string label;
    };

sale.cpp

// 清单15.15
    #include "sales.h"
    using std::string;
    
    Sales::bad_index::bad_index(int ix, const string & s) : std::logic_error(s), bi(ix)
    {
    }
    
    Sales::Sales(int yy)
    {
        year = yy;
        for (int i = 0; i < MONTHS; i++)
        {
            gross[i] = 0;
        }
    }
    
    Sales::Sales(int yy, const double * gr, int n)
    {
        year = yy;
        int lim = (n < MONTHS) ? n : MONTHS;
        int i;
        for (i = 0; i < lim; ++i)
        {
            gross[i] = gr[i];
        }
        for (; i < MONTHS; ++i)
        {
            gross[i] = 0;
        }
    }
    
    double Sales::operator[](int i) const
    {
        if (i < 0 || i >= MONTHS)
        {
            throw bad_index(i);
        }
        return gross[i];
    }
    
    double & Sales::operator[](int i)
    {
        if (i < 0 || i >= MONTHS)
        {
            throw bad_index(i);
        }
        return gross[i];
    }
    
    LabeledSales::nbad_index::nbad_index(const string & lb, int ix, const string & s) : Sales::bad_index(ix, s)
    {
        lbl = lb;
    }
    
    LabeledSales::LabeledSales(const string & lb, int yy) : Sales(yy)
    {
        label = lb;
    }
    
    LabeledSales::LabeledSales(const string & lb, int yy, const double * gr, int n) : Sales(yy, gr, n)
    {
        label = lb;
    }
    
    double LabeledSales::operator[](int i) const
    {
        if (i < 0 || i >= MONTHS)
        {
            throw nbad_index(Label(), i);
        }
        return Sales::operator[](i);
    }
    
    double & LabeledSales::operator[](int i)
    {
        if (i < 0 || i >= MONTHS)
        {
            throw nbad_index(Label(), i);
        }
        return Sales::operator[](i);
    }

play.cpp

// 改自清单15.16
    #include <iostream>
    #include "sales.h"
    
    int main()
    {
        using namespace std;
        double vals1[12] =
                {
                        1220, 1100, 1122, 2212, 1232, 2334,
                        2884, 2393, 3302, 2922, 3002, 3544
                };
        double vals2[12] =
                {
                        12, 11, 22, 21, 32, 34,
                        28, 29, 33, 29, 32, 35
                };
    
        Sales sales1(2011, vals1, 12);
        LabeledSales sales2("Blogstar", 2012, vals2, 12);
        Sales::bad_index * S;
        LabeledSales::nbad_index * L;
    
        cout << "First try block:\n";
        try
        {
            int i;
            cout << "Year = " << sales1.Year() << endl;
            for (i = 0; i < 12; ++i)
            {
                cout << sales1[i] << ' ';
                if (i % 6 == 5)
                    cout << endl;
            }
            cout << "Year = " << sales2.Year() << endl;
            cout << "Label = " << sales2.Label() << endl;
            for (i = 0; i <= 12; ++i)
            {
                cout << sales2[i] << ' ';
                if (i % 6 == 5)
                    cout << endl;
            }
            cout << "End of try block 1.\n";
        }
        catch (logic_error & bad)
        {
            cout << bad.what();
            if (L = dynamic_cast<LabeledSales::nbad_index *>(&bad))
            {
                cout << "Company: " << L->label_val() << endl;
                cout << "Bad index: " << L->bi_val() << endl;
            }
            else if (S = dynamic_cast<Sales::bad_index *>(&bad))
            {
                cout << "Bad index: " << S->bi_val() << endl;
            }
        }
        cout << "\nNext try block:\n";
        try
        {
            sales2[2] = 37.5;
            sales1[20] = 23345;
            cout << "End of try block 2.\n";
        }
        catch (logic_error & bad)
        {
            cout << bad.what();
            if (L = dynamic_cast<LabeledSales::nbad_index *>(&bad))
            {
                cout << "Company: " << L->label_val() << endl;
                cout << "Bad index: " << L->bi_val() << endl;
            }
            else if (S = dynamic_cast<Sales::bad_index *>(&bad))
            {
                cout << "Bad index: " << S->bi_val() << endl;
            }
        }
        cout << "done\n";
    
        return 0;
    }

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