添加友元

base/CMakeLists.txt

@@ -60,4 +60,4 @@ 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(tv friend/tv.cpp)
+add_executable(tv friend/tv.cpp friend/use_tv.cpp friend/tvfm.h)

base/friend/tvfm.h

@@ -0,0 +1,109 @@
+//
+// Created by zhuyi on 2021/9/3.
+//
+
+#ifndef BASE_TVFM_H
+#define BASE_TVFM_H
+
+class Tv;
+
+class Remote{
+public:
+    enum State{
+        OFF, ON
+    };
+    enum {
+        MinVal, MaxVal = 20
+    };
+    enum {
+        Antenna, Cable
+    };
+    enum {
+        TV, DVD
+    };
+private:
+    int mode;
+public:
+    Remote(int m = TV):mode(m){}
+    bool volup(Tv & t);
+    bool voldown(Tv & t);
+    void onoff(Tv & t);
+
+    bool chanup(Tv & t);
+    void chandown(Tv & t);
+    void set_chan(Tv & t,int c);
+    void set_mode(Tv & t);
+    void set_input(Tv & t);
+};
+
+
+class Tv {
+
+public:
+    friend void Remote::set_chan(Tv &t, int c);
+    enum State{
+        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;
+};
+
+inline bool Remote::volup(Tv & t){
+    return t.volup();
+};
+inline bool Remote::voldown(Tv & t){
+    return t.voldown();
+};
+inline void Remote::onoff(Tv & t) { t.onoff(); }
+
+inline bool Remote::chanup(Tv & t){
+    t.chanup();
+};
+inline void Remote::chandown(Tv & t){
+    t.chandown();
+};
+inline void Remote::set_chan(Tv & t,int c){
+    t.channel = c;
+}
+inline void Remote::set_mode(Tv & t){
+    t.set_mode();
+}
+inline void Remote::set_input(Tv & t){
+    t.set_input();
+}
+
+
+#endif //BASE_TVFM_H

base/friend/use_tv.cpp

@@ -0,0 +1,33 @@
+//
+// Created by zhuyi on 2021/9/3.
+//
+#include <iostream>
+#include "tv.h"
+
+int main(){
+    using std::cout;
+    using std::endl;
+    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 usinfg remote:\n";
+    s42.settings();
+
+    Tv s58(Tv::ON);
+    s58.set_mode();
+    grey.set_chan(s58,28);
+    cout <<"\n58\" settings:\n";
+    s58.settings();
+    return 0;
+}
+