Converting integers to roman numerals

Question

I'm trying to write a function that converts numbers to roman numerals. This is my code so far; however, it only works with numbers that are less than 400. Is there a quick and easy way to do this conversion, or extend my existing code so that it handles all cases? Thanks in advance for any help.

static string convertroman(int number)     {         int l = number / 10;         StringBuilder sb = new StringBuilder();         for (int m = 0; m <= l; m++)         {             if (l == 0)             {                 break;             }             if (l == 5)             {                 sb = sb.Append(ro.L.ToString());                 break;             }             if (l == 4)             {                 sb = sb.Append(ro.X.ToString()).Append(ro.L.ToString());                 break;             }             if (l == 9)             {                 sb = sb.Append(ro.X.ToString()).Append(ro.C.ToString());                 break;             }             if (l == 10)             {                 sb = sb.Append(ro.C.ToString());                 break;             }              if (l > 5 && l < 9)             {                 sb = sb.Append(ro.L.ToString());                 l = l - 5;                 m = 0;                 // break;                 continue;             }             if (l > 10)             {                 sb = sb.Append(ro.C.ToString());                 l = l - 10;                 m = 0;                 // continue;              }             else             {                 sb = sb.Append(ro.X.ToString());             }          }         int z = number % 10;         for (int x = 0; x <= z; x++)         {             if (z == 0)             {                 break;             }             if (z == 5)             {                 sb = sb.Append(ro.V.ToString());                 break;             }             if (z == 4)             {                 sb = sb.Append(ro.I.ToString()).Append(ro.V.ToString());                 break;             }             if (z == 9)             {                 sb = sb.Append(ro.I.ToString()).Append(ro.X.ToString());                 break;             }             if (z == 10)             {                 sb = sb.Append(ro.X.ToString());                 break;             }             if (z > 5 && z < 9)             {                 sb = sb.Append(ro.V.ToString());                 z = z - 5;                 x = 0;             }             else             {                 sb.Append(ro.I.ToString());             }                        }         return sb.ToString();                } 

Answer 1

Try this, simple and compact:

public static string ToRoman(int number) {     if ((number < 0) || (number > 3999)) throw new ArgumentOutOfRangeException("insert value betwheen 1 and 3999");     if (number < 1) return string.Empty;                 if (number >= 1000) return "M" + ToRoman(number - 1000);     if (number >= 900) return "CM" + ToRoman(number - 900);      if (number >= 500) return "D" + ToRoman(number - 500);     if (number >= 400) return "CD" + ToRoman(number - 400);     if (number >= 100) return "C" + ToRoman(number - 100);                 if (number >= 90) return "XC" + ToRoman(number - 90);     if (number >= 50) return "L" + ToRoman(number - 50);     if (number >= 40) return "XL" + ToRoman(number - 40);     if (number >= 10) return "X" + ToRoman(number - 10);     if (number >= 9) return "IX" + ToRoman(number - 9);     if (number >= 5) return "V" + ToRoman(number - 5);     if (number >= 4) return "IV" + ToRoman(number - 4);     if (number >= 1) return "I" + ToRoman(number - 1);     throw new ArgumentOutOfRangeException("something bad happened"); }