How to re-ask for input in try catch statement

Question

string l = Console.ReadLine();

try
{
    int.Parse(l);
}
catch (FormatException)
{
    Console.WriteLine("Invalid input. Please enter 1, 2, or 3.");
}

As you can see, I have asked for input, but if the user enters a non-integral answer such as the letter "f", the catch statement catches it, but then throws the exception again afterwards, because the variable "l" still equals "f". Help?

Answer 1

You can use int.TryParse instead of catching exceptions. It returns whether the parse was successful, so you can check it in a loop until the input is valid e.g.

int i;
bool valid = false;
do {
    Console.WriteLine("Enter an int: ");
    string input = Console.ReadLine();
    valid = int.TryParse(input, out i);
} while(! valid);

//use i