第十五章 编程练习

编程练习1

//tv.h#ifndef TV_H_#define TV_H_#include <iostream>class Tv{public:    friend class Remote;    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 ChangeReMode(Remote & r);private:    int state;    int volume;    int maxchannel;    int channel;    int mode;    int input;};class Remote{private:    int mode;    int ReMode;public:    friend class Tv;    enum {Normal, Interactive};    Remote(int m = Tv::TV, int n = Normal):mode(m), ReMode(n) {}    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 ShowReMode() const { std::cout << "Remote now is at " << (ReMode == Normal? "Normal" : "Interactive") << std::endl;}};#endif

//tv.cpp#include "tv.h"#include <iostream>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;    }}void Tv::ChangeReMode(Remote & r){    if (state == On)        r.ReMode ^=1;}

//use_tv.cpp#include <iostream>#include "tv.h"int main(){    using std::cout;    Tv s42;    cout << "Initial settings for 42\" Tv:\n";    s42.settings();    s42.onoff();    s42.chanup();    cout << "\nAdjusted settings for 42\" TV:\n";    s42.chanup();    cout << "\nAdjusted settings for 42\" TV:\n";    s42.settings();    Remote grey;    grey.set_chan(s42, 10);    grey.volup(s42);    grey.volup(s42);    cout << "\n42\" settings after using remote:\n";    s42.settings();    grey.ShowReMode();    s42.ChangeReMode(grey);    grey.ShowReMode();    system("pause");    return 0;}

编程练习2

//exc_mean.h#ifndef EXC_MEAN_H_#define EXC_MEAN_H_#include <iostream>#include <stdexcept>#include <string>class bad_hmean : public std::logic_error{public:    bad_hmean(const std::string &s = "hmean(), invalid argument") : logic_error(s) {}};class bad_gmean : public std::logic_error{public:    bad_gmean(const std::string &s = "gmean(), auguments shouble be >= 0") : logic_error(s) {}};#endif

//use exc_mean.cpp#include <iostream>#include <cmath>#include "exc_mean.h"double hmean(double a, double b);double gmean(double a, double b);int main(){    using std::cout;    using std::cin;    using std::endl;    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 quite>: ";        }        catch (bad_hmean & bg)        {            cout << bg.what() << endl;;            cout << "Try again.\n";                continue;        }        catch(bad_gmean & hg)        {            cout << hg.what() << endl;;            cout << "Sorry, you don't get to play any more.\n";            break;        }    }    cout << "Bye!\n";    system("pause");    return 0;}double hmean(double a, double b){    if (a == -b)        throw bad_hmean();    return 2 * a *b /(a+b);}double gmean(double a, double b){    if (a<0 || b<0)        throw bad_gmean();    return std::sqrt(a * b);}

编程练习3

//exc_mean.h#ifndef EXC_MEAN_H_#define EXC_MEAN_H_#include <iostream>#include <stdexcept>#include <string>class bad_hmean : public std::logic_error{private:    double v1, v2;public:    bad_hmean(double x = 0, double y =  0) : std::logic_error("hmean") { v1 = x; v2 = y; }    virtual void what() { std::cout << "hmean(), invalid argument. a = " << v1 << ", b = " << v2 << std::endl; }};class bad_gmean : public std::logic_error{private:    double v1, v2;public:    bad_gmean(double x = 0, double y = 0) : logic_error("gmean") { v1 = x; v2 = y; }    virtual void what() { std::cout << "gmean(), auguments shouble be >= 0. a = " << v1 << ", b = " << v2 << std::endl; }};#endif

//use exc_mean.cpp#include <iostream>#include <cmath>#include "exc_mean.h"double hmean(double a, double b);double gmean(double a, double b);int main(){    using std::cout;    using std::cin;    using std::endl;    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 quite>: ";        }        catch (bad_hmean & bg)        {            bg.what();            cout << "Try again.\n";                continue;        }        catch(bad_gmean & hg)        {            hg.what();            cout << "Sorry, you don't get to play any more.\n";            break;        }    }    cout << "Bye!\n";    system("pause");    return 0;}double hmean(double a, double b){    if (a == -b)        throw bad_hmean(a, b);    return 2 * a *b /(a+b);}double gmean(double a, double b){    if (a<0 || b<0)        throw bad_gmean(a, b);    return std::sqrt(a * b);}

编程练习4

主函数修改即可

#include <iostream>#include "sales.h"int main(){    using std::cout;    using std::cin;    using std::endl;    using std::logic_error;    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);    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 & le)    {        cout << le.what();        if(LabeledSales::nbad_index *ni = dynamic_cast<LabeledSales::nbad_index *>(&le))        {            cout << "Company: " << ni->label_val() << endl;            cout << "bad index: " << ni->bi_val() << endl;        }        else if(Sales::bad_index *bi = dynamic_cast<Sales::bad_index *>(&le))            cout << "bad index: " << bi->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 & le)    {        cout << le.what();        if(LabeledSales::nbad_index *ni = dynamic_cast<LabeledSales::nbad_index *>(&le))        {            cout << "Company: " << ni->label_val() << endl;            cout << "bad index: " << ni->bi_val() << endl;        }        else if(Sales::bad_index *bi = dynamic_cast<Sales::bad_index *>(&le))            cout << "bad index: " << bi->bi_val() << endl;    }    cout << "done\n";    system("pause");    return 0;}