/******************************** 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;
}