Regular expression to split string and number

Question

I have a string of the form:

codename123

Is there a regular expression that can be used with Regex.Split() to split the alphabetic part and the numeric part into a two-element string array?

Answer 1

A little verbose, but

Regex.Split( "codename123", @"(?<=[a-zA-Z])(?=\d)" );

Can you be more specific about your requirements? Maybe a few other input examples.

Answer 2

splitArray = Regex.Split("codename123", @"(?<=\p{L})(?=\p{N})");

will split between a Unicode letter and a Unicode digit.

Answer 3

I know you asked for the Split method, but as an alternative you could use named capturing groups:

var numAlpha = new Regex("(?<Alpha>[a-zA-Z]*)(?<Numeric>[0-9]*)");
var match = numAlpha.Match("codename123");

var alpha = match.Groups["Alpha"].Value;
var num = match.Groups["Numeric"].Value;

Answer 4

Regex is a little heavy handed for this, if your string is always of that form. You could use

"codename123".IndexOfAny(new char[] {'1','2','3','4','5','6','7','8','9','0'})

and two calls to Substring.

Answer 5

IMO, it would be a lot easier to find matches, like:

Regex.Matches("codename123", @"[a-zA-Z]+|\d+")
     .Cast<Match>()
     .Select(m => m.Value)
     .ToArray();

rather than to use Regex.Split.