text: #include <iostream>
  #include "tv.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
  {
      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;
      }
  }
  