Validating input value from console without exiting loop C#

Question

Lets say for a console application, I want the user to enter how many dices he would like to throw. Onlu values 1-5 will be accepted. I tried doing this:

Console.WriteLine("How many dices would you like to throw?");
int amount = Convert.ToInt32(Console.ReadLine());

while(true)
{
 if(amount < 1 || amount > 5)
 {
     Console.WriteLine("Please enter a value between 1-5");
     break;
 } 
}

The problem here is that if the user enters an invalid number, the program stops. I want it to simply continue asking until correct value is inputed. Any ideas?

cheers.

For what it's worth... The word "dice" is plural in English (the singular is "die" - really). — Flydog57
– Flydog57, Commented Jun 1, 2020 at 17:36

Nazim · Accepted Answer · 2020-06-01 17:29:31Z

1

I haven't tested it but slightly refactored your code as below, it should do what you want:

Console.WriteLine("How many dices would you like to throw?");
int amount = Convert.ToInt32(Console.ReadLine());

while(amount < 1 || amount > 5)
{
    Console.WriteLine("Please enter a value between 1-5");
    amount = Convert.ToInt32(Console.ReadLine());
}

EDIT: if you want to safely check whether it is an integer value, you can use the below version of code:

    Console.WriteLine("How many dices would you like to throw?");
    var input = Console.ReadLine();

    while(!int.TryParse(input, out int amount) || amount < 1 || amount > 5)
    {
        Console.WriteLine("Please enter a value between 1-5");
        input = Console.ReadLine();
    }

edited Jun 1, 2020 at 17:29

answered Jun 1, 2020 at 17:17

Nazim

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1 Comment

user1892117 Over a year ago

Problem here is that everytime the user enters an invalid int, the question to enter a value should output. This solution only let the user enter any other number...

Barns · Accepted Answer · 2020-06-01 17:39:54Z

You might want to check if the entered value is actually an integer.

        int amount;
        Console.WriteLine("How many dices would you like to throw?");
        do
        {
            if (int.TryParse(Console.ReadLine(), out var i))
            {
                if (i >= 1 && i <= 5)
                {
                    amount = i;
                    break;
                }
                Console.WriteLine("The integer value is not between 1 and 5");
            }
            {
                Console.WriteLine("The value you entered is not an integer");
            }
        } while (true);

EDIT
I generally like to give the user the option to exit completely.

        int amount;
        Console.WriteLine("How many dices would you like to throw? Or enter 'X' to exit.");
        do
        {
            var input = Console.ReadLine();
            if(input.Equals("X", StringComparison.InvariantCultureIgnoreCase))
            {
                return;
            }

            if (int.TryParse(input, out var i))
            {
                if (i >= 1 && i <= 5)
                {
                    amount = i;
                    break;
                }
                Console.WriteLine("The integer value is not between 1 and 5");
            }
            {
                Console.WriteLine("The value you entered is not an integer");
            }
        } while (true);

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