add arabic to roman converter

2 files changed, 28 insertions, 1 deletions

diff --git a/snc.c b/snc.c
index d42dce2..818bc78 100644
--- a/snc.c
+++ b/snc.c
@@ -18,6 +18,8 @@
 ***/
 
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include "snc.h"
 
@@ -80,6 +82,29 @@ int romanToArabic(char *str)
 	return answer;
 }
 
+char *arabicToRoman(char *str)
+{
+	int number = atoi(str);
+	if(!number || number > SNC_ROMAN_MAX_NUMBER)
+		return NULL;
+
+	const char *units[] = {"","I","II","III","IV",
+							"V","VI","VII","VIII","IV"};
+	const char *tens[] = {"","X","XX","XXX","XL",
+							"L","LX","LXX","LXXX","XC"};
+	const char *hundreds[] = {"","C","CC","CCC","CD",
+							"D","DC","DCC","DCCC","CM"};
+	const char *thousands[] = {"","M","MM","MMM"};
+	char *answer = malloc(sizeof(char) * (SNC_ROMAN_MAXLEN + 1));
+
+	strcpy(answer, thousands[number / 1000]);
+	strcat(answer, hundreds[number / 100 % 10]);
+	strcat(answer, tens[number / 10 % 10]);
+	strcat(answer, units[number % 10]);
+
+	return answer;
+}
+
 int main(int argc, char *argv[])
 {
 	if(argc < 2)
diff --git a/snc.h b/snc.h
index b100151..9b02b51 100644
--- a/snc.h
+++ b/snc.h
@@ -27,7 +27,9 @@ enum {
 	SNC_ROMAN_L = 50,
 	SNC_ROMAN_C = 100,
 	SNC_ROMAN_D = 500,
-	SNC_ROMAN_M = 1000
+	SNC_ROMAN_M = 1000,
+	SNC_ROMAN_MAX_NUMBER = 3999,
+	SNC_ROMAN_MAXLEN = 15 // MMMDCCCLXXXVIII
 };
 
 #endif /* SNC_NUMBERS_H */