/*
 **************************************************************************
 * Program name : 016_Palindrome_number (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 : 2000/06/09 - first version                              *
 **************************************************************************
 * Description  : (a) Input an integer number                             *
 *                (b) Is that a palindrome number ?                       *
 *                (e) Try again ?                                         *
 **************************************************************************
*/
#include <iostream.h>
#include <stdlib.h>
#include <math.h>                                                    // Note (1)
#include <iomanip.h>                                                 // Note (2)

int main()
{
 // part 1 : declaration
 int   Number, Size, Div, Index, TempNum, Comp_1, Comp_2;
 char  Pali, again;

 cout << "The palindrome is a number or a text phrase that reads the same\n"
      << "backwards as forwards. For example : 12321, 55555 and 45554.\n";
 do {
     // part 2 : Repeat asking the valus of base amount until base amount > 0
     do {
         cout << "\nPlease input an integer number : ";
         cin  >> Number;
         if (Number<=0)                                         // Note (3)
           {
            cout << "\nThe number must be greater than zero(o)!";
            continue;
           };

         // part 3 : Find the length of the inpuuted number
         Div  = 1;
         Size = 0;
         for (Index=1; Index<=10; Index++)                      // Note (4)
           {
            Div  *= 10;
            Size += 1;
            if ((Number / Div)==0) break;
           }
         cout << "\nThe inputted number is : " << Number;
         cout << "\nNo. of digit is        : " << Size << endl;
         if ((Size % 2)==0 || Size==1)                          // Note (5)
           {
            cout << "\nThis program need an integer "
                 << "with 3,5,7 or 9 digits. \nPlease try again!\n";
            continue;
           };
        } while ((Number<=0) || (Size % 2)==0 || (Size == 1));

     // part 4 : Is that a palindrome number ?
     Pali = 'Y';
     TempNum = Number;                                               // Note (6)
     Index = 1;                                                      // Note (7)
     cout << "\nRound      Number     First   Last      Result\n"
          << "-------------------------------------------------------------\n";
     do {
        Comp_1 = TempNum % 10;                                       // Note (8)
        Comp_2 = TempNum /(pow(10,Size-1));                          // Note (9)
        cout << Index << "\t" << setw(9) << TempNum << "\t"
             << Comp_1 << "\t" << Comp_2;
        if (Comp_1 != Comp_2)                                       // Note (10)
          {
           cout << "\tError found\n";
           Pali = 'N';
           break;
          }
        else
          {
           TempNum = (TempNum-(Comp_2*pow(10,Size-1)))/10;          // Note (11)
           Size -= 2;
           Index++;
           cout << "\tPass, " << Size << " digit(s) left\n";
          };
        } while (Size!=1);
     if (Pali=='Y')
       cout << "\a\n" <<Number << " is a pailndrome number.\n\n";
     else cout << "\a\n" << Number << " is not a pailndrome number.\n\n";

     // part 5 : try another number ?
     cout << "\aTry another number (Y/N) : ";
     cin  >> again;
     cout << "\n";
    } while (again=='Y' || again=='y');
 cout << "\n" << endl;

 system("PAUSE");
 return 0;
}

/* Notes
   (1) Use "#include <math.h>" because this program needs the function "pow".
   (2) Use "#include <iomanip.h>" because this program needs the function "setw".
   (3) This program does not support negative number.
   (4) Check the no. of digit inputted:

       Example : 12321

       Index     Div      Size    Number/Div
         1       10       1       1232
         2       100      2       123
         3       1000     3       12
         4       10000    4       1
         5       100000   5       0 (stop checking when Number/Div is 0)

       Therefore the number 12321 contains 5 digits.

   (5) When ((Size % 2)==0 || Size==1), that means the no. of digits is an
       even number or that number contains one digit only.
       However this program does not support negative number.
   (6) Use the variable "TempNum" to represent the value of "Number" in
       the loop of checking.
   (7) Use "Index" to keeps the number of round.
   (8) Use "TempNum % 10" to find the last digit then stored in "Comp_1".
   (9) Use "TempNum /(pow(10,Size-1))" to find the first digit then
       stored in "Comp_2".
  (10) When (Comp_1 != Comp_2), that means the inputted number is not a
       palindrome number.
  (11) Find the value of TempNum for the next round:

       Example : 1234221

       Round     TempNum  first(comp_2)  last(comp_1)    Reault
       ------------------------------------------------------------------------
       1         1234221  1              1               Pass, 5 digit(s) left
       2           23422  2              2               Pass, 3 digit(s) left
       3             342  3              2               Error found

       When TempNum is 23422 and Size is 5, then
         pow(10,Size-1)                       == 10000
         Comp_2*pow(10,Size-1)                == 20000
         TempNum-(Comp_2*pow(10,Size-1))      == 3422
         (TempNum-(Comp_2*pow(10,Size-1)))/10 == 342
         TempNum                              == 342 (for the next round)
*/