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/******************************** R2A_ENG.C *********************************/
/* Created by: Manuel F Mart¡nez.                          manpaz@email.com */
/* Lenguage:   C/C++                                                        */
/* Date:       Guatemala May 19, 2002                                       */
/* ************************************************************************ *//* Object:  Convert an roman numeral to arabical, the input can be a number */
/*          between 1 to 3999.                                              */
/* Description:  The program take each letter and store it in one letter    */
/*               array, after convert each letter and store it in the same  */
/*               position of one numbers array.                             *//*                                                                          */
/*             In this array be analized if is a number of two letters or   */
/*             one letter;  if is of two letters do a  difference  if the   */
/*             pair is correctly write, and this value is amounted to the   */
/*             integer variable that  store the result, and if the number   *//*             is of  one letter  only  amount  the value  of this  roman   */
/*             letter.                                                      */
/****************************************************************************/
/* NOTE:  IF YOU USE VISUAL C++, FIRST CREATE A WORKSPACE, SECOND CLEAR THE */
/*        LINE "clrscr();" THEN COMPILE THE PROGRAM.                        *//****************************************************************************/
 
/* Header files */
#include <conio.h>;
#include <ctype.h>;#include <stdio.h>;
#include <dos.h>;
 
int main (void) {
   int numR = 0;        /* Decimal value of roman numeral      */   int decR = 0;        /* Decimal value of each roman numeral */
   int cont = 0;        /* String position                     */
   int cont3R = 0;      /* 3 incurs counter                    */
   int numsR[15] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
                        /* Array that store the value of each                           roman letter                        */
   char letterR = ' ';  /* Contain the temporal roman letter   */
   char roman[15] = ""; /* Contain the input string            */
 
   /* Clear the screen and display the input message */   clrscr();
   printf ("Enter a roman numeral between range I to MMMCMXCIX:n");
 
   /* Read from keyboard until appear an <ENTER> */
   while ((letterR != 'n') && (cont < 15)) {      letterR = toupper(getchar());
 
      switch (letterR) {
         /* V, L y D only can appear one time */
         case 'V': case 'L': case 'D':            /* If appear more of one time, then finish the program */
            if ((cont > 0) && (roman[cont - 1] == letterR)) {
                  printf ("nData incorrect");
                  delay (1000);
                  exit (0);            }
 
            /* If appear one time, be save the char in the string that
               store the characters of roman numeral                   */
            else { roman[cont++] = letterR; }            break;
 
         /* I, X, C y M can appear until 3 times */
         case 'I': case 'X': case 'C': case 'M':
            /* If appear correctly, be save the char in the string that               that store the characters of roman numeral              */
            if (cont3R <= 3) {
               roman[cont++] = letterR;
            }
            cont3R++;            /* If appear more of 3 times, then finish the program */
            if ((cont3R > 3) && (roman[cont - 2] == letterR)) {
               printf ("nData incorrect");
               delay (1000);
               exit (0);            }
            /* If the 3 incurs counter get to be 3 but the preceding char
               is different of current, then reset the 3 incurs counter   */
            if ((cont > 1) && ((cont3R > 3) || (roman[cont - 2] != letterR))) {
               cont3R = 1;            }
            break;
         /* Invalidate the n char as default char */
         case 'n':   break;
          /* If the input is a char that not concern to roman numerals,
            then finish the program                                    */
         default:    printf ("nData incorrect");
                     delay (1000);
                     exit (0);     }
   }
 
   /* Reutilization of cont3R var as index of iterations for no create
      a new var and then optimize the program                          */ 
   /* Convert to decimal each letter of roman numeral that was input */
   for (cont3R = 0; cont3R <= cont; cont3R++) {
      switch (roman[cont3R]) {
      case 'I':   numsR[cont3R] = 1;      break;      case 'V':   numsR[cont3R] = 5;      break;
      case 'X':   numsR[cont3R] = 10;     break;
      case 'L':   numsR[cont3R] = 50;     break;
      case 'C':   numsR[cont3R] = 100;    break;
      case 'D':   numsR[cont3R] = 500;    break;      case 'M':   numsR[cont3R] = 1000;   break;
      }
   }
 
   /* Do a sum over stored numbers */   for (cont3R = 0; cont3R <= cont; cont3R++) {
      /* */
      /* Add decimal value of each roman numeral */
      if (numsR[cont3R] >= numsR[cont3R + 1]) {
         decR = numsR[cont3R];      }
      /* If precedent number is less than current value and this is 10%
         or 5% of current value, then do a difference between two roman
         numerals to obtain the final value i.e. IX = 10 - 1 = 9        */
      if ((numsR[cont3R] == (numsR[cont3R + 1] / 10))          || (numsR[cont3R] == (numsR[cont3R + 1] / 5))) {
         decR = numsR[cont3R + 1] - numsR[cont3R];
         cont3R++;
      }
      /* If precedent numbre is less than current value and not is 10% or         5% of current value, then finish the program                    */
      if (decR < numsR[cont3R + 1]) {
          printf ("nData incorrect");
          delay (1000);
          exit (0);      }
      numR += decR;
   }
 
   /* Diplay result in the screen */   printf ("The value is %d", numR);
 
   /* Press any key to finish the program */
   printf ("nnttt...Press any key to exit.");
   getch(); 
   /* Return succesfully */
   return 0;
}