Refactoring to remove try/catch

Question

Any ideas on a good way to refactor this so that my code acts the same, but without the whole throwing and catching my own exception?

public Int32 ChooseNextColor(Int32 numColors)
{
    int? nextColor = null;

    while (nextColor == null)
    {
        Console.Write("Please enter your next color selection: ");
        string input = Console.ReadLine();

        try
        {
            nextColor = Convert.ToInt32(input);
            if (nextColor > numColors || nextColor < 0) 
                throw new ArgumentOutOfRangeException();
        }
        catch
        {
            nextColor = null;
            Console.WriteLine("Unrecognized input: " + input);
            Console.WriteLine("Please enter a value between 0 and " + numColors + ".");
        }
    }

    return (nextColor.Value);
}

EDIT: The try/parse method is exactly what I am looking for.

In response to John's title edit -> I should have posted more information to begin with, and that would have been "getting rid of the try/catch all together is best". So with that in mind, I changed the title.

Answer 1

You can use Int32.TryParse() or

if (nextColor > numColors || nextColor < 0) 
    {
        Console.WriteLine("Unrecognized input: " + input);
        Console.WriteLine("Please enter a value between 0 and " + numColors + ".");
        return null;
    }

Answer 2

.NET provides TryParse for just this reason.

Answer 3

Try

int nextColor;
input = Console.ReadLine();

while( ! Int32.TryParse( input, out nextColor ) 
       || nextColor > numColors 
       || nextColor < 0 )
{ 
    Console.WriteLine("Unrecognized input: " + input);
    Console.WriteLine("Please enter a value between 0 and " + numColors + ".");
    input = Console.ReadLine();
}

Answer 4

If you want to avoid exception, you should use int.TryParse method instead of Convert.ToInt32().

Answer 5

warning, not tested!

public int ChooseNextColor(int numColors)
{
    while (true)
    {
        Console.Write("Please enter your next color selection: ");
        string input = Console.ReadLine();
        int color;
        if (!int.TryParse(input, out color) || color > numColors || color < 0)
        {
            Console.WriteLine("Unrecognized input: " + input);
            Console.WriteLine("Please enter a value between 0 and " + numColors + ".");
        }
        else
        {
            return color;
        }
    }
}

Answer 6

    public Int32 ChooseNextColor(Int32 numColors)
    {
        var success = false;
        while (!success)
        {
            Console.Write("Please enter your next color selection: ");
            int nextColor;
            var input = Console.ReadLine();
            success = int.TryParse(input, out nextColor);

            if (success && nextColor > 0 && nextColor < numColors) return nextColor;

            Console.WriteLine("Unrecognized input: " + input);
            Console.WriteLine("Please enter a value between 0 and " + numColors + ".");
        }
        throw new ApplicationException("The thing that should not be.");
    }