【C++ Primer Plus】编程练习答案——第15章

【【C++ Primer Plus】编程练习答案——第15章】1 // chapter15_1_tvremote.h23 #ifndef LEARN_CPP_CHAPTER15_1_TVREMOTE_H4 #define LEARN_CPP_CHAPTER15_1_TVREMOTE_H5 class Remote;6 class Tv {7 private:8int state;9int volume; 10int maxchannel; 11int channel; 12int mode; 13int input; 14 public: 15friend class Remote; 16enum {OFF, ON}; 17enum {MinVal, MaxVal = 20}; 18enum {Antenna, Cable}; 19enum {TV, DVD}; 2021Tv(int s = OFF, int mc = 125) : state(s), volume(5), maxchannel(mc), channel(2), mode(Cable), input(TV) {} 22void onoff() {state = (state == ON)? OFF : ON;} 23bool ison() const {return state == ON;} 24bool volup(); 25bool voldown(); 26void chanup(); 27void chandown(); 28void set_mode() {mode = (mode == Antenna)? Cable : Antenna;} 29void set_input() {input = (input == TV)? DVD : TV;} 30void settings() const; 31void set_status(Remote & r); 32 }; 3334 class Remote { 35 private: 36int mode; 37int status; // 常规还是互动模式 38 public: 39friend class Tv; 40enum {Normal, Interacte}; 4142Remote(int m = Tv::TV) : mode(m), status(Normal){} 43bool volup(Tv & t) {return t.volup();} 44bool voldown(Tv & t) {return t.voldown();} 45void onoff(Tv & t) {t.onoff();} 46void chanup(Tv & t) {t.chanup();} 47void chandown(Tv & t) {t.chandown();} 48void set_chan(Tv & t, int c) {t.channel = c;} 49void set_input(Tv & t) {t.set_input();} 50void showstatus() const; 51 }; 525354 #endif //LEARN_CPP_CHAPTER15_1_TVREMOTE_H 555657 // chapter15_1_tvremote.cpp 5859 #include "chapter15_1_tvremote.h" 60 #include <iostream> 6162 bool Tv::volup() { 63if (volume < MaxVal) { 64++ volume; 65return true; 66} 67return false; 68 } 6970 bool Tv::voldown() { 71if (volume > MinVal) { 72-- volume; 73return true; 74} 75return false; 76 } 7778 void Tv::chanup() { 79if (channel < maxchannel) 80++ channel; 81else 82channel = 1; 83 } 8485 void Tv::chandown() { 86if (channel > 1) 87-- channel; 88else 89channel = maxchannel; 90 } 9192 void Tv::settings() const { 93using namespace std; 94cout << "TV is " << (state == OFF? "OFF" : "ON") << endl; 95if (state == ON) { 96cout << "volume setting = " << volume << endl; 97cout << "channel setting = " << channel << endl; 98cout << "mode = " << (mode == Antenna? "antenna" : "cable") << endl; 99cout << "input = " << (input == TV? "TV" : "DVD") << endl;100}101 }102 103 void Tv::set_status(Remote &r) {104if (state == ON)105r.status = r.status == Remote::Interacte? Remote::Normal : Remote::Interacte;106 }107 108 void Remote::showstatus() const {109using namespace std;110cout << "status = " << (status == Interacte? "Interacte" : "Normal") << endl;111 }112 113 // run114 115 void ch15_1() {116using namespace std;117Tv s42;118cout << "Initial settings for 42\" TV:\n";119s42.settings();120s42.onoff();121s42.chanup();122s42.chanup();123cout << "\nAdjusted settings for 42\" TV:\n";124s42.settings();125 126Remote grey;127grey.set_chan(s42, 10);128grey.volup(s42);129grey.volup(s42);130cout << "\n42\" settings after using remote:\n";131s42.settings();132 133Tv s58(Tv::ON);134s58.set_mode();135grey.set_chan(s58, 28);136cout << "\n58\" settings:\n";137s58.settings();138 139cout << "\n58\" status:\n";140grey.showstatus();141s58.set_status(grey);142grey.showstatus();143 } 1 // chapter15_2_stdexcept.h 23 #ifndef LEARN_CPP_CHAPTER15_2_STDEXCEPT_H 4 #define LEARN_CPP_CHAPTER15_2_STDEXCEPT_H 56 #include <stdexcept> 7 #include <cmath> 89 class meanlogicerr : public std::logic_error {10 public:11meanlogicerr() : logic_error("") {}12const char * what() {return "bad arguments to hmean() or gmean()";}13 };14 15 #endif //LEARN_CPP_CHAPTER15_2_STDEXCEPT_H16 17 // run18 19 double hmean(double a, double b) {20if (a == b)21throw meanlogicerr();22return 2.0 * a * b / (a + b);23 }24 25 double gmean(double a, double b) {26if (a < 0 || b < 0)27throw meanlogicerr();28return std::sqrt(a * b);29 }30 31 void ch15_2() {32using namespace std;33try {cout << "x = 1, y = 1, hmean = " << hmean(1, 1) << endl;}34catch (meanlogicerr & me) {cout << me.what() << endl;}35try {cout << "x = -1, y = 1, gmean = " << gmean(-1, 1) << endl;}36catch (meanlogicerr & me) {cout << me.what() << endl;}37try {cout << "x = 1, y = 2, hmean = " << hmean(1, 2) << endl;}38catch (meanlogicerr & me) {cout << me.what() << endl;}39try {cout << "x = 1, y = 1, gmean = " << gmean(1, 1) << endl;}40catch (meanlogicerr & me) {cout << me.what() << endl;}41 } 1 // chapter15_3_meanerr.h 23 #ifndef LEARN_CPP_CHAPTER15_3_MEANERR_H 4 #define LEARN_CPP_CHAPTER15_3_MEANERR_H 56 #include <stdexcept> 7 #include <iostream> 8 #include <string> 9 10 class twodouargserr : public std::logic_error {11 private:12double arg1;13double arg2;14std::string funcname;15 public:16twodouargserr(double a1 = 0, double a2 = 0, const char * f = "none")17: arg1(a1), arg2(a2), funcname(f), std::logic_error("") {}18virtual const char * what() {return "invalid args";}19virtual void msg(){std::cout << funcname << "() logicerr, arg1: " << arg1 << " arg2: " << arg2 << std::endl;}20 };21 22 class hmean_err : public twodouargserr {23 public:24hmean_err(double a1 = 0, double a2 = 0, const char * f = "none")25: twodouargserr(a1, a2, f) {}26virtual const char * what() {return "invalid args";}27virtual void msg(){twodouargserr::msg();}28 };29 30 class gmean_err : public twodouargserr {31 public:32gmean_err(double a1 = 0, double a2 = 0, const char * f = "none")33: twodouargserr(a1, a2, f) {}34virtual const char * what() {return "invalid args";}35virtual void msg(){twodouargserr::msg();}36 };37 38 39 #endif //LEARN_CPP_CHAPTER15_3_MEANERR_H40 41 // run42 43 double hmean2(double a, double b) {44if (a == b)45throw hmean_err(a, b, __func__ );46return 2.0 * a * b / (a + b);47 }48 49 double gmean2(double a, double b) {50if (a < 0 || b < 0)51throw gmean_err(a, b, __func__ );52return std::sqrt(a * b);53 }54 void ch15_3() {55using namespace std;56try {cout << "x = 1, y = 1, hmean = " << hmean2(1, 1) << endl;}57catch (hmean_err & he) {cout << he.what() << endl; he.msg();}58try {cout << "x = 1, y = 2, hmean = " << hmean2(1, 2) << endl;}59catch (hmean_err & he) {cout << he.what() << endl; he.msg();}60try {cout << "x = -1, y = 1, gmean = " << gmean2(-1, 1) << endl;}61catch (gmean_err & ge) {cout << ge.what() << endl; ge.msg();}62try {cout << "x = 1, y = 1, hmean = " << gmean2(1, 1) << endl;}63catch (gmean_err & ge) {cout << ge.what() << endl; ge.msg();}64 }剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。剩下的有空写。。