.net version

using System;
using Microsoft.Win32;

public class GetDotNetVersion
{
   public static void Main()
   {
      GetDotNetVersion.Get45PlusFromRegistry();
   }

   private static void Get45PlusFromRegistry()
   {
      const string subkey = @"SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full\";

   	using (RegistryKey ndpKey = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry32).OpenSubKey(subkey))
      {
   		if (ndpKey != null && ndpKey.GetValue("Release") != null) {
   			Console.WriteLine(".NET Framework Version: " + CheckFor45PlusVersion((int) ndpKey.GetValue("Release")));
   		}
         else {
            Console.WriteLine(".NET Framework Version 4.5 or later is not detected.");
         } 
   	}
   }

   // Checking the version using >= will enable forward compatibility.
   private static string CheckFor45PlusVersion(int releaseKey)
   {
      if (releaseKey >= 461308)
         return "4.7.1 or later";
      if (releaseKey >= 460798)
         return "4.7";
      if (releaseKey >= 394802)
         return "4.6.2";
      if (releaseKey >= 394254) {
         return "4.6.1";
      }
      if (releaseKey >= 393295) {
         return "4.6";
      }
      if ((releaseKey >= 379893)) {
         return "4.5.2";
      }
      if ((releaseKey >= 378675)) {
         return "4.5.1";
      }
      if ((releaseKey >= 378389)) {
   	   return "4.5";
      }
   	// This code should never execute. A non-null release key should mean
   	// that 4.5 or later is installed.
   	return "No 4.5 or later version detected";
   }
}   
// This example displays output like the following:
//       .NET Framework Version: 4.6.1