Hi.  How about this?

using System;
using System.Diagnostics;
using System.IO;
using System.Reflection;
using System.Resources;

public static string Version()
{
    var x86Folderpath = Environment.GetFolderPath(Environment.SpecialFolder.ProgramFilesX86);
    const string exeRelativepath = @"SDL\SDL Trados Studio\Studio4\SDLTradosStudio.exe";
    var exeFullpath = Path.Combine(x86Folderpath, exeRelativepath);
    var assembly = Assembly.LoadFrom(exeFullpath);
    var resourceManager = new ResourceManager("Sdl.TranslationStudio.Application.StringResources", assembly);
    var version = string.Format(resourceManager.GetString("Version"),
        $"- {FileVersionInfo.GetVersionInfo(exeFullpath).FileVersion}");
    return version;
}

Hi hiroshi kameya ,

If you download from Nuget: Sdl.Community.Toolkit.Core you'll be able to see all Studio versions installed on the machine.

To do so you need a instance of StudioVersionService :

var studioService = new StudioVersionService();
var studioList = studioService.GetInstalledStudioVersions();

Kind regards,

Andrea Ghisa.