C# code to detect which version of the .NET Framework is installed

After searching on google for a simple method to get the current installed version of the .NET Framework, I decided to implement my own. I have put this method in its own class, because there are probably a lot of other similar methods that could be grouped together.

using System;
using System.IO;
using System.Security;
using System.Text.RegularExpressions;

namespace YourNameSpace
{
    public class SystemInfo
    {
        private const string FRAMEWORK_PATH = "\\Microsoft.NET\\Framework";
        private const string WINDIR1 = "windir";
        private const string WINDIR2 = "SystemRoot";

        public static string FrameworkVersion
        {
            get
            {
                try
                {
                    return getHighestVersion(NetFrameworkInstallationPath);
                }
                catch (SecurityException)
                {
                    return "Unknown";
                }
            }
        }

        private static string getHighestVersion(string installationPath)
        {
            string[] versions = Directory.GetDirectories(installationPath, "v*");
            string version = "Unknown";

            for (int i = versions.Length - 1; i >= 0; i--)
            {
                version = extractVersion(versions[i]);
                if (isNumber(version))
                    return version;
            }

            return version;
        }

        private static string extractVersion(string directory)
        {
            int startIndex = directory.LastIndexOf("\\") + 2;
            return directory.Substring(startIndex, directory.Length - startIndex);
        }

        private static bool isNumber(string str)
        {
            return new Regex(@"^[0-9]+\.?[0-9]*$").IsMatch(str);
        }

        public static string NetFrameworkInstallationPath
        {
            get { return WindowsPath + FRAMEWORK_PATH; }
        }

        public static string WindowsPath
        {
            get
            {
                string winDir = Environment.GetEnvironmentVariable(WINDIR1);
                if (String.IsNullOrEmpty(winDir))
                    winDir = Environment.GetEnvironmentVariable(WINDIR2);

                return winDir;
            }
        }
    }
}

How it works? It searches the .NET Framework installation folder and returns the highest version installed on the system based on the folder names. I think the code is straightforward. I’d like to know other people’s thoughts and ideas. I know about other ways (registry keys, etc). I also hope this code helps other people to save some time.

Tags: .NET, C#, installation, Path, Version