/*
 **************************************************************************
 * Program name : 012_Prime_number_or_not (Version 1.00)                  *
 * Author       : Duck Wong                                               *
 * Language     : C / C++                                                 *
 * Compiler     : Boodshed Dec-C++ compiler Ver 3.95                      *
 * Computer     : PII350                                                  *
 * O/S          : Windows 98                                              *
 **************************************************************************
 * Version 1.00 : 2000/06/08 - first version                              *
 **************************************************************************
 * Description  : (a) Input an integer number                             *
 *                (b) Is that a prime number ?                            *
 *                (c) Output results                                      *
 **************************************************************************
*/
#include <iostream.h>
#include <stdlib.h>

int main()
{
      // part 1 : declaration
      int Inputnum, Index;
      char Status, again;

      // part 2
      do {
          // (a) input an integer
          do {
              cout << "Please enter an integer number : ";
              cin  >> Inputnum;
             } while (Inputnum<=0);                          // Note (1)

          // (b) check the status
          Status='N';
          for (Index=2; Index<=((Inputnum+1)/2); Index++)
            {
             if ((Inputnum % Index)== 0)                     // Note (2)
               {
                Status='Y';
                break;
               }
            };

          // (c) output
          if (Status=='Y' ? cout << Inputnum << " is not a prime number"
              : cout << Inputnum << " is a prime number");   // Note (3)

          // (d) try another number ?
          cout << "\a\n\nTry another number (Y/N) : ";
          cin  >> again;

        } while (again=='Y' || again=='y');
      cout << "\n\n" << endl;

      system("PAUSE");
      return 0;
}

/* Notes

   (1) The inputed integer number must be greater than zero.
   (2) If the remainder of Inputnum over Index is zero, then Inputnum is not
       a prime number.
   (3) operator ?:

       example :
                 if (Status=='Y' ? cout << Inputnum << " is not a prime number"
                     : cout << Inputnum << " is a prime number");

       is eaual to the following statements :

                 if (Status=='Y')
                   cout << Inputnum << " is not a prime number";
                 else cout << Inputnum << " is a prime number";
*/