Question

I have some problem with a method that I have done in c#. I’m trying to stop user from entering anything else then y and n. It’s almost working that I want, but user can still enter more than one sign, and then it doesn’t work! How can I do to also check if char is more than one char? I thought the tryParse solved that? Thanks!

// Method to check if item is food or not
    private void ReadIfFoodItem()
    {
        Console.Write("Enter if food item or not (y/n): ");

        if (char.TryParse(Console.ReadLine(), out responseFoodItem))
        {
            if(Char.IsNumber(responseFoodItem))
            {
                Console.WriteLine(errorMessage);
                ReadIfFoodItem();
            }
            else
            {
                // Set true or false to variable depending on the response
                if ((responseFoodItem == 'y' || responseFoodItem == 'Y'))
                {
                    foodItem = true;
                    selectedVATRate = 12; // Extra variable to store type of VAT
                }
                else if ((responseFoodItem == 'n' || responseFoodItem == 'N'))
                {
                    foodItem = false;
                    selectedVATRate = 25; // Extra variable to store type of VAT
                }
                else
                {
                    Console.WriteLine(errorMessage);
                    ReadIfFoodItem();
                }
            }
        }
    }

Answer 1

The following code “works” in that it produces the expected results.

        char responseFoodItem;

        Console.Write("Enter if food item or not (y/n): ");

        if (char.TryParse(Console.ReadLine(), out responseFoodItem))
        {
            // Set true or false to variable depending on the response
            if ((responseFoodItem == 'y' || responseFoodItem == 'Y'))
            {
                Console.WriteLine("foodItem = true");
            }
            else if ((responseFoodItem == 'n' || responseFoodItem == 'N'))
            {
                Console.WriteLine("foodItem = false");
            }
            else
            {
                Console.WriteLine("Unrecognised input");
            }
        }
        else
        {
            Console.WriteLine("Invalid input");
        }

However, has others have pointed out using ReadKey is a better solution if you want to limit the input to a single key. It also means that the user doesn’t have to press the Return/Enter key for the input to be accepted.