Question

How do I add a regular expression which will accept decimal places (5.23) but nothing else in a break like so? i.e handle only numbers and decimal places which will throw an error if anything other than this is typed or returned:

    case 1:
    double[] myArrai1 = new double[3];
    Console.WriteLine("Insert a number");
    myArrai1[0] = double.TryParse(Console.ReadLine()); // no overload method?
     Console.WriteLine("Insert a number");
     myArrai1[1] = double.Parse(Console.ReadLine());
    Console.WriteLine("Insert a number");
    myArrai1[2] = double.Parse(Console.ReadLine());
    break;

Cheers guys.

P.s not sure on how to programme it in with the break also has to be without exception.

Answer 1

Did you want to just validate what the user inputs, or stop them from putting in invalid characters in the first place?

In the first case, regex aren’t really needed. You are on the right track with double.Parse, but what you want to do is double.TryParse. First read the user input into a string, then TryParse it into a double. If TryParse returns false, tell you user their input is invalid and prompt them to enter it again.

FWIW: here’s how I’d do it (warning: untested code), which may or may not be what you need:

case 1:
double[] myArrai1 = new double[3];
for (int i=0; i < myArrai1.length; i++) {
    Console.WriteLine("Insert a number");
    while (!double.TryParse(Console.Readline(), out myArrai1[i])) {
        Console.WriteLine("Invalid entry. Please enter a number.");
    }
}
break;