Cadena de Conexion C# y SQL Server

    public class Config
    {
        protected SqlConnection cnn = new SqlConnection();
        public bool Conectado()
        {
            try{
                string cadena = "data source =localhost; initial catalog=SisAvikarDemo; User Id=Naoemi; Password=Pantagarcia";
                cnn = new SqlConnection(cadena);
                cnn.Open();
                return true;
            }catch (Exception){
                return false;
            }
        }
        public bool Desconectado(){
            if(cnn.State == System.Data.ConnectionState.Open){
                cnn.Close();
                return true;
            }
            return true;
        }
    }