private void Get45or451FromRegistry()
        {
            using (RegistryKey ndpKey = Registry.LocalMachine.OpenSubKey("SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full\"))
            {
                if (ndpKey != null && ndpKey.GetValue("Release") != null)
                {
                    versions += "\nv" + CheckFor45DotVersion((int)ndpKey.GetValue("Release"));
                }
                else
                {
                    versions += "Version 4.5 or later is not detected.";
                }
            }
        }
        private string CheckFor45DotVersion(int releaseKey)
        {
            if (releaseKey == 394254 || releaseKey == 394271)
            {
                return "4.6.1";
            }
            if (releaseKey >= 393295)
            {
                return "4.6 or later";
            }
            if ((releaseKey >= 379893))
            {
                return "4.5.2 or later";
            }
            if ((releaseKey >= 378675))
            {
                return "4.5.1 or later";
            }
            if ((releaseKey >= 378389))
            {
                return "4.5 or later";
            }
            // This line 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";
        }

那directX有没有同样的方法去判断注册表？     或判断系统文件夹有没有用相应的exe？
求详细代码，非常感谢！