c# - Regex Pattern number1 to number2

Question

I'm searching for a pattern for the following behavior:

number1-number2
number1: Can be everything >= 0 and <= int.MaxValue
number2: Can be everything >= number1 and <= int.MaxValue

e.g.

"1-2" => True
"0-0" => True
"10-22" => True
"22-10" => False
"10-10" => True
"a-b" => False

It would be also nice if I could directly extract the two int values.

Answer 1

You cannot use a regex for comparing extracted numbers. You need to parse the values with int.TryParse and implement other checks to get what you need.

Assuming you only have integer positive numbers in the ranges, here is a String.Split and int.TryParse approach:

private bool CheckMyRange(string number_range, ref int n1, ref int n2)
{
    var rng = number_range.Split('-');
    if (rng.GetLength(0) != 2) 
       return false;

    if (!int.TryParse(rng[0], out n1))
       return false;
    if (!int.TryParse(rng[1], out n2))
       return false;
    if (n1 >= 0 && n1 <= int.MaxValue)
       if (n2 >= n1 && n2 <= int.MaxValue)
           return true;
    return false;
}

And call it like

int n1 = -1;
int n2 = -1;
bool result = CheckMyRange("1-2", ref n1, ref n2);