32位程序访问64位系统上的Windows注册表

  public static string GetSQLServerInstallPath()
        {
            string SQLPath = string.Empty;
            
            RegistryKey hkml = Registry.LocalMachine;
            RegistryKey MSSQLServerKey = hkml.OpenSubKey(@"SOFTWARE\MICROSOFT\MSSQLServer");
            if (MSSQLServerKey != null)
            {
                string[] keys = MSSQLServerKey.GetSubKeyNames();
                RegistryKey setupKey = MSSQLServerKey.OpenSubKey("Setup");
                if(setupKey!=null)
                {
                    SQLPath = setupKey.GetValue("SQLPath").ToString();
                }
              else                 
                {
                    SQLPath = Get64BitRegistryKey(RegistryHive.LocalMachine, @"SOFTWARE\MICROSOFT\MSSQLServer\Setup", "SQLPath", RegistryView.Registry64);
                }
            }
            return SQLPath;
        }

        /// <summary>
        /// this method is use for the 32appliction to get the 64bit regestkey
        /// </summary>
        /// <param name="parentKeyName"></param>
        /// <param name="subKeyName"></param>
        /// <param name="keyName"></param>
        /// <returns></returns>
        public static string Get64BitRegistryKey(RegistryHive hive,string keyName,string valueName,RegistryView view)
        {
            Microsoft.Win32.SafeHandles.SafeRegistryHandle handle = new Microsoft.Win32.SafeHandles.SafeRegistryHandle(GetHiveHandle(hive),true);
            RegistryKey subkey = RegistryKey.FromHandle(handle, view).OpenSubKey(keyName);
            RegistryKey key = RegistryKey.FromHandle(subkey.Handle, view);
            return key.GetValue(valueName).ToString();

        }

        static IntPtr GetHiveHandle(RegistryHive hive)
        {
            IntPtr preexistingHandle = IntPtr.Zero;

            IntPtr HKEY_CLASSES_ROOT = new IntPtr(-2147483648);
            IntPtr HKEY_CURRENT_USER = new IntPtr(-2147483647);
            IntPtr HKEY_LOCAL_MACHINE = new IntPtr(-2147483646);
            IntPtr HKEY_USERS = new IntPtr(-2147483645);
            IntPtr HKEY_PERFORMANCE_DATA = new IntPtr(-2147483644);
            IntPtr HKEY_CURRENT_CONFIG = new IntPtr(-2147483643);
            IntPtr HKEY_DYN_DATA = new IntPtr(-2147483642);
            switch (hive)
            {
                case RegistryHive.ClassesRoot: preexistingHandle = HKEY_CLASSES_ROOT; break;
                case RegistryHive.CurrentUser: preexistingHandle = HKEY_CURRENT_USER; break;
                case RegistryHive.LocalMachine: preexistingHandle = HKEY_LOCAL_MACHINE; break;
                case RegistryHive.Users: preexistingHandle = HKEY_USERS; break;
                case RegistryHive.PerformanceData: preexistingHandle = HKEY_PERFORMANCE_DATA; break;
                case RegistryHive.CurrentConfig: preexistingHandle = HKEY_CURRENT_CONFIG; break;
                case RegistryHive.DynData: preexistingHandle = HKEY_DYN_DATA; break;
            }
            return preexistingHandle;
        }