Question

Here is my code, which takes two version identifiers in the form ‘1, 5, 0, 4’ or ‘1.5.0.4’ and determines which is the newer version.

Suggestions or improvements, please!

    /// <summary>     /// Compares two specified version strings and returns an integer that      /// indicates their relationship to one another in the sort order.     /// </summary>     /// <param name='strA'>the first version</param>     /// <param name='strB'>the second version</param>     /// <returns>less than zero if strA is less than strB, equal to zero if     /// strA equals strB, and greater than zero if strA is greater than strB</returns>     public static int CompareVersions(string strA, string strB)     {         char[] splitTokens = new char[] {'.', ','};         string[] strAsplit = strA.Split(splitTokens, StringSplitOptions.RemoveEmptyEntries);         string[] strBsplit = strB.Split(splitTokens, StringSplitOptions.RemoveEmptyEntries);         int[] versionA = new int[4];         int[] versionB = new int[4];          for (int i = 0; i < 4; i++)         {             versionA[i] = Convert.ToInt32(strAsplit[i]);             versionB[i] = Convert.ToInt32(strBsplit[i]);         }          // now that we have parsed the input strings, compare them         return RecursiveCompareArrays(versionA, versionB, 0);     }      /// <summary>     /// Recursive function for comparing arrays, 0-index is highest priority     /// </summary>     private static int RecursiveCompareArrays(int[] versionA, int[] versionB, int idx)     {         if (versionA[idx] < versionB[idx])             return -1;         else if (versionA[idx] > versionB[idx])             return 1;         else         {             Debug.Assert(versionA[idx] == versionB[idx]);             if (idx == versionA.Length - 1)                 return 0;             else                 return RecursiveCompareArrays(versionA, versionB, idx + 1);         }     } 

---

@ Darren Kopp:

The version class does not handle versions of the format 1.0.0.5.

Answer 1

The System.Version class does not support versions with commas in it, so the solution presented by Darren Kopp is not sufficient.

Here is a version that is as simple as possible (but no simpler).

It uses System.Version but achieves compatibility with version numbers like ‘1, 2, 3, 4’ by doing a search-replace before comparing.

    /// <summary>     /// Compare versions of form '1,2,3,4' or '1.2.3.4'. Throws FormatException     /// in case of invalid version.     /// </summary>     /// <param name='strA'>the first version</param>     /// <param name='strB'>the second version</param>     /// <returns>less than zero if strA is less than strB, equal to zero if     /// strA equals strB, and greater than zero if strA is greater than strB</returns>     public static int CompareVersions(String strA, String strB)     {         Version vA = new Version(strA.Replace(',', '.'));         Version vB = new Version(strB.Replace(',', '.'));          return vA.CompareTo(vB);     } 

The code has been tested with:

    static void Main(string[] args)     {         Test('1.0.0.0', '1.0.0.1', -1);         Test('1.0.0.1', '1.0.0.0', 1);         Test('1.0.0.0', '1.0.0.0', 0);         Test('1, 0.0.0', '1.0.0.0', 0);         Test('9, 5, 1, 44', '3.4.5.6', 1);         Test('1, 5, 1, 44', '3.4.5.6', -1);         Test('6,5,4,3', '6.5.4.3', 0);          try         {             CompareVersions('2, 3, 4 - 4', '1,2,3,4');             Console.WriteLine('Exception should have been thrown');         }         catch (FormatException e)         {             Console.WriteLine('Got exception as expected.');         }          Console.ReadLine();     }      private static void Test(string lhs, string rhs, int expected)     {         int result = CompareVersions(lhs, rhs);         Console.WriteLine('Test(\'' + lhs + '\', \'' + rhs + '\', ' + expected +             (result.Equals(expected) ? ' succeeded.' : ' failed.'));     }