添加友元

base/CMakeLists.txt

@@ -59,4 +59,5 @@ add_executable(studentc reusing/studentc.cpp)
 add_executable(uses_stuc reusing/uses_stuc.cpp)
 add_executable(stacktp stl/stacktp.cpp)
 add_executable(stacktp1 stl/stacktp1.cpp)
-add_executable(arraytp stl/arraytp.cpp)
+add_executable(arraytp stl/arraytp.cpp)
+add_executable(tv friend/tv.cpp)

base/friend/tv.cpp

@@ -0,0 +1,50 @@
+//
+// Created by nicemoe on 2021/9/2.
+//
+
+#include  <iostream>
+#include "tv.h"
+
+bool Tv::volup() {
+    if (volume < MaxVal) {
+        volume++;
+        return true;
+    }
+    return false;
+}
+
+bool Tv::voldown() {
+    if (volume > MinVal) {
+        volume--;
+        return true;
+    }
+    return false;
+}
+
+bool 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;
+    }
+}

base/friend/tv.h

@@ -0,0 +1,84 @@
+//
+// Created by nicemoe on 2021/9/2.
+//
+
+#ifndef BASE_TV_H
+#define BASE_TV_H
+
+
+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();
+    bool 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(); }
+
+    bool 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();
+    }
+};
+
+#endif //BASE_TV_H