Question

Not entirely sure this is possible, but say I have two strings like so:

"IAmAString-00001"
"IAmAString-00023"

What would be a quick’n’easy way to iterate from IAmAString-0001 to IAmAString-00023 by moving up the index of just the numbers on the end?

The problem is a bit more general than that, for example the string I could be dealing could be of any format but the last bunch of chars will always be numbers, so something like Super_Confusing-String#w00t0003 and in that case the last 0003 would be what I’d use to iterate through.

Any ideas?

Answer 1

string start = "IAmAString-00001";
string end = "IAmAString-00023";

// match constant part and ending digits
var matchstart = Regex.Match(start,@"^(.*?)(\d+)$");
int numberstart = int.Parse(matchstart.Groups[2].Value);

var matchend = Regex.Match(end,@"^(.*?)(\d+)$");
int numberend = int.Parse(matchend.Groups[2].Value);

// constant parts must be the same
if (matchstart.Groups[1].Value != matchend.Groups[1].Value)
    throw new ArgumentException("");

// create a format string with same number of digits as original
string format = new string('0', matchstart.Groups[2].Length);

for (int ii = numberstart; ii <= numberend; ++ii)
    Console.WriteLine(matchstart.Groups[1].Value + ii.ToString(format));