List all SQL Instances on a local machine in C#

This is just another SQL C# articles which let you learn how to make a list of names of SQL instance available on your Microsoft SQL Server using C# code.

This is made possible using Registry entries.

     private IEnumerable<string> ListLocalSqlInstances(RegistryKey hive)
        {
            const string keyName = @"Software\Microsoft\Microsoft SQL Server";
            const string valueName = "InstalledInstances";
            const string defaultName = "MSSQLSERVER";

            using (var key = hive.OpenSubKey(keyName, false))
            {
                if (key == null) return Enumerable.Empty<string>();

                var value = key.GetValue(valueName) as string[];
                if (value == null) return Enumerable.Empty<string>();

                for (int index = 0; index < value.Length; index++)
                {
                    if (string.Equals(value[index], defaultName, StringComparison.OrdinalIgnoreCase))
                    {
                        value[index] = ".";
                    }
                    else
                    {
                        value[index] = @".\" + value[index];
                    }
                }

                return value;
            }
        }


 public IEnumerable<string> ListLocalSqlInstances()
        {
            if (Environment.Is64BitOperatingSystem)
            {
                using (var hive = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry64))
                {
                    foreach (string item in ListLocalSqlInstances(hive))
                    {
                        yield return item;
                    }
                }

                using (var hive = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry32))
                {
                    foreach (string item in ListLocalSqlInstances(hive))
                    {
                        yield return item;
                    }
                }
            }
            else
            {
                foreach (string item in ListLocalSqlInstances(Registry.LocalMachine))
                {
                    yield return item;
                }
            }
        }

How to use the function

The function has two part, one with argument which dig for registry element another will extract the information.

 txt_instance.ItemsSource = SqlHelper.ListLocalSqlInstances();

The a above line will serve the list of string ( instance names ) and serve as itemsource for a combo box control.