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C++-练习-109

news 2026/5/28 11:32:16

题目：

对Tv和Remote类进行如下修改

a.让它们互为友元

b.在Remote类中添加一个状态变量成员，该成员描述遥控器使处于常规状态还是互动模式

c.在Remote中添加一个显式模式的方法

d.在Tv类中添加一个对Remote中新成员进行切换的方法，该方法仅当Tv处于打开状态是才能运行

编写一个小程序来测试这些新特性

#ifndef QUEUE_H_ #define QUEUE_H_ #include <iostream> using namespace std; class Tv { public: friend class Remote; enum { Off, On }; enum { MinuVal, 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; private: int state; int volume; int maxchannel; int channel; int mode; int input; }; class Remote { private: int mode; public: Remote(int m = Tv::TV) : mode(m) {} 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(); } }; #e

源代码：

test.h

#ifndef QUEUE_H_ #define QUEUE_H_ #include <iostream> using namespace std; class Remote; 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 set_Remode(Remote& r); private: int state; //是否开机 int volume; //音量 int maxchannel; //最大频道 int channel; //当前频道 int mode; //广播或有线 int input; //TV或DVD }; class Remote { public: enum { Normal, InterActive }; //状态类型 private: int mode; int work_mode; //添加状态变量 public: friend class Tv; Remote(int m = Tv::TV,int work = Normal) : mode(m) , work_mode(work) {} 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(); } int show_mode() const { return work_mode; } }; #endif inline void Tv::set_Remode(Remote& r) { r.work_mode = (r.work_mode == Remote::Normal) ? Remote::InterActive : Remote::Normal; }

test_function.cpp

#include "test.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 { 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; } }

test.cpp

#include <iostream> #include "test.h" int main() { Tv s42; cout << "Initial ettings for 42\" TV:\n"; s42.settings(); s42.onoff(); 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(); Tv s58(Tv::On); s58.set_mode(); grey.set_chan(s58, 28); cout << "\n58\" settings:\n"; s58.settings(); cout << "\n\nRemote work_mode: " << (grey.show_mode() == Remote::Normal ? "Normal" : "InterActive") << endl; s58.set_Remode(grey); cout << "Remote work_mode: " << (grey.show_mode() == Remote::Normal ? "Normal" : "InterActive") << endl; return 0; }

演示效果：

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