public static void MainMenu() { string path = String.Format(@"C:\Users\{0}\Documents\allquerys.json", Environment.UserName); File.Delete(path); int num = -1; int opt = 0; Console.WriteLine(); Console.Title = "CalculatorService by SrG"; Console.WriteLine("Welcome and greetings \n"); do { Console.WriteLine("What you want to do?"); Console.WriteLine("0 - Exit"); Console.WriteLine("1 - Sign up"); Console.WriteLine("2 - Sign in"); Console.WriteLine("3 - Sign as a guest"); ConsoleKeyInfo UserInput = Console.ReadKey(); // Get user input // We check input for a Digit if (char.IsDigit(UserInput.KeyChar)) { num = int.Parse(UserInput.KeyChar.ToString()); // use Parse if it's a Digit } if (num < -1 || num > 3) { Console.Clear(); Console.WriteLine("\nPlease, introduce one of the following\n"); } } while (num < 0 && 3 < num); switch (num) { case 0: break; case 1: Client.SignUp(); break; case 2: Client.SignIn(); break; case 3: // sign as guest id = -1; break; default: Console.Clear(); Console.WriteLine("\n\nPlease, introduce one of the following\n"); break; } do { Console.Clear(); Console.WriteLine("\nWhat do you want to do?\n"); Console.WriteLine("0 - Exit"); Console.WriteLine("1 - Addition"); Console.WriteLine("2 - Substraction"); Console.WriteLine("3 - Multiplication"); Console.WriteLine("4 - Division"); Console.WriteLine("5 - Square root"); Console.WriteLine("6 - Journal query\n"); ConsoleKeyInfo UserInput = Console.ReadKey(); // Get user input // We check input for a Digit if (char.IsDigit(UserInput.KeyChar)) { opt = int.Parse(UserInput.KeyChar.ToString()); // use Parse if it's a Digit } switch (opt) { case 0: break; case 1: Client.Addition(id); break; case 2: Client.Substraction(id); break; case 3: Client.Multiplication(id); break; case 4: Client.Division(id); break; case 5: Client.SquareRoot(id); break; case 6: Client.JournalQuery(); break; default: Console.Clear(); Console.WriteLine("\n\nPlease, introduce one of the following\n"); break; } } while (opt != 0); }