using System;

public class Program

{

    public static void Main()

    {

        Test_CompareVersionStrings();

    }

    /// <summary>

    /// Compare two version strings, e.g.  "3.2.1.0.b40" and "3.10.1.a".

    /// V1 and V2 can have different number of components.

    /// Components must be delimited by dot.

    /// </summary>

    /// <remarks>

    /// This doesn't do any null/empty checks so please don't pass dumb parameters

    /// </remarks>

    /// <param name="v1"></param>

    /// <param name="v2"></param>

    /// <returns>

    /// -1 if v1 is lower version number than v2,

    /// 0 if v1 == v2,

    /// 1 if v1 is higher version number than v2,

    /// -1000 if we couldn't figure it out (something went wrong)

    /// </returns>

    private static int CompareVersionStrings(string v1, string v2)

    {

        int rc = -1000;

​

        v1 = v1.ToLower();

        v2 = v2.ToLower();

​

        if (v1 == v2)

            return 0;

​

        string[] v1parts = v1.Split('.');

        string[] v2parts = v2.Split('.');

​

        for (int i = 0; i < v1parts.Length; i++)

        {

            if (v2parts.Length < i+1)

                break; // we're done here

            string v1Token = v1parts[i];

            string v2Token = v2parts[i];

            int x;

            bool v1Numeric = int.TryParse(v1Token, out x);

            bool v2Numeric = int.TryParse(v2Token, out x);

            // handle scenario {"2" versus "20"} by prepending zeroes, e.g. it would become {"02" versus "20"}

            if (v1Numeric && v2Numeric) {

                while (v1Token.Length < v2Token.Length)

                    v1Token = "0" + v1Token;

                while (v2Token.Length < v1Token.Length)

                    v2Token = "0" + v2Token;

            }

​

            rc = String.Compare(v1Token, v2Token, StringComparison.Ordinal);

            //Console.WriteLine("v1Token=" + v1Token + " v2Token=" + v2Token + " rc=" + rc);

            if (rc != 0)

                break;

        }

​

        if (rc == 0)

        {

            // catch this scenario: v1="1.0.1" v2="1.0"

            if (v1parts.Length > v2parts.Length)

                rc = 1; // v1 is higher version than v2

            // catch this scenario: v1="1.0" v2="1.0.1"

            else if (v2parts.Length > v1parts.Length)

                rc = -1; // v1 is lower version than v2

        }

​

        if (rc == 0 || rc == -1000)

            return rc;

        else

            return rc < 0 ? -1 : 1;

    }

    private static int _CompareVersionStrings(string v1, string v2)

    {

        int rc = CompareVersionStrings(v1, v2);

        Console.WriteLine("Compare v1: " + v1 + "  v2: " + v2 + "  result: " + rc);

        return rc;

    }

​

    // for debugging

    private static void Test_CompareVersionStrings()

    {

        bool allPass = true;

​

        // should be equal

        allPass &= (0 == _CompareVersionStrings("1", "1"));

        allPass &= (0 == _CompareVersionStrings("1.1", "1.1"));

        allPass &= (0 == _CompareVersionStrings("3.3.a20", "3.3.A20"));

​

        // v1 should be lower

        allPass &= (-1 == _CompareVersionStrings("1", "2"));

        allPass &= (-1 == _CompareVersionStrings("1.0", "1.0.1"));

        allPass &= (-1 == _CompareVersionStrings("1.0", "1.1"));

        allPass &= (-1 == _CompareVersionStrings("1.0.0.3", "1.1"));

        allPass &= (-1 == _CompareVersionStrings("1.2.3.4", "1.2.3.4b"));

        allPass &= (-1 == _CompareVersionStrings("1.2.3.4", "1.2.3.4.b"));

        allPass &= (-1 == _CompareVersionStrings("1.8.0", "20.0.0.0"));

        allPass &= (-1 == _CompareVersionStrings("5.6.0.788.2", "20.0.0.0"));

​

        // v1 should be higher

        allPass &= (1 == _CompareVersionStrings("2", "1"));

        allPass &= (1 == _CompareVersionStrings("1.0.1", "1.0"));

        allPass &= (1 == _CompareVersionStrings("1.1", "1.0"));

        allPass &= (1 == _CompareVersionStrings("1.1", "1.0.0.3"));

        allPass &= (1 == _CompareVersionStrings("1.2.3.4b", "1.2.3.4"));

        allPass &= (1 == _CompareVersionStrings("1.2.3.4.b", "1.2.3.4")); 

        allPass &= (1 == _CompareVersionStrings("20.0.0.0", "5.6.0.788.2"));

​

        Console.WriteLine("allPass = " + allPass.ToString());

    }   

}