times1.cpp

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//times1.cpp
//converts from time24 to time12 using operator in time24
#include <iostream>
#include <string>
using namespace std;
////////////////////////////////////////////////////////////////
class time12
   {
   private:
      bool pm;                       //true = pm, false = am
      int hrs;                       //1 to 12
      int mins;                      //0 to 59
   public:                           //no-arg constructor
      time12() : pm(true), hrs(0), mins(0)
         {  }
                                     //3-arg constructor
      time12(bool ap, int h, int m) : pm(ap), hrs(h), mins(m)
         {  }
      void display() const           //format: 11:59 p.m.    
         {
         cout << hrs << ':';
         if(mins < 10)
            cout << '0';             //extra zero for "01"             
         cout << mins << ' ';
         string am_pm = pm ? "p.m." : "a.m.";
         cout << am_pm;
         }
   };
////////////////////////////////////////////////////////////////
class time24
   {
   private:
      int hours;                     //0 to 23
      int minutes;                   //0 to 59
      int seconds;                   //0 to 59
   public:                           //no-arg constructor
      time24() : hours(0), minutes(0), seconds(0)
         {  }                                     
      time24(int h, int m, int s) :  //3-arg constructor
              hours(h), minutes(m), seconds(s)
         {  }
      void display() const           //format: 23:15:01
         {
         if(hours < 10)    cout << '0';
         cout << hours << ':';
         if(minutes < 10)  cout << '0';
         cout << minutes << ':';
         if(seconds < 10)  cout << '0';
         cout << seconds;
         }
      operator time12() const;       //conversion operator
   };
//--------------------------------------------------------------
time24::operator time12() const           //conversion operator
   {
   int hrs24 = hours;
   bool pm = hours < 12 ? false : true;   //find am/pm
                                          //round secs                    
   int roundMins = seconds < 30 ? minutes : minutes+1;
   if(roundMins == 60)                    //carry mins?
      {
      roundMins=0;
      ++hrs24;
      if(hrs24 == 12 || hrs24 == 24)      //carry hrs?
         pm = (pm==true) ? false : true;  //toggle am/pm
      }
   int hrs12 = (hrs24 < 13) ? hrs24 : hrs24-12;
   if(hrs12==0)                           //00 is 12 a.m.
      { hrs12=12; pm=false; }
   return time12(pm, hrs12, roundMins);
   }
////////////////////////////////////////////////////////////////
int main()
   {
   int h, m, s;

   while(true)
      {                              //get 24-hr time from user
      cout << "Enter 24-hour time: \n";
      cout << "   Hours (0 to 23): "; cin >> h;
      if(h > 23)                     //quit if hours > 23
         return(1);
      cout << "   Minutes: ";  cin >> m;
      cout << "   Seconds: ";  cin >> s;

      time24 t24(h, m, s);           //make a time24
      cout << "You entered: ";       //display the time24
      t24.display();

      time12 t12 = t24;              //convert time24 to time12

      cout << "\n12-hour time: ";    //display equivalent time12
      t12.display();             
      cout << "\n\n";
      }
   return 0;
   }