Question

Suppose I had the string “1 AND 2 AND 3 OR 4”, and want to create an array of strings that contains all substrings “AND” or “OR”, in order, found within the string.

So the above string would return a string array of {“AND”, “AND”, “OR”}.

What would be a smart way of writing that?

EDIT:
Using C# 2.0+,

string rule = "1 AND 2 AND 3 OR 4";
string pattern = "(AND|OR)";
string[] conditions = Regex.Split(rule, pattern);

gives me {“1”, “AND”, “2”, “AND”, “3”, “OR”, “4”}, which isn’t quite what I’m after. How can I reduce that to the ANDs and ORs only?

Answer 1

This regex (.NET) seems to do what you want. You’re looking for the matches (multiple) in the group at index=1:

.*?((AND)|(OR))*.*?

EDIT I’ve tested the following and it seems to do what you want. It’s more lines than i would like but it approaches the task in a purely regex fashion (which IMHO is what you should be doing):

        string text = "1 AND 2 AND 3 OR 4";
        string pattern = @"AND|OR";

        Regex r = new Regex(pattern, RegexOptions.IgnoreCase);

        Match m = r.Match(text);
        ArrayList results = new ArrayList();
        while (m.Success)
        {
            results.Add(m.Groups[0].Value);

            m = m.NextMatch();
        }

        string[] matchesStringArray = (string[])results.ToArray(typeof(string));