Regex.Matches Fails To Find Multiple Matches

Question

I have run into a problem when trying to find multiple matches in a length of text. The text has the following format:

string text = "#IDENTIFIER http://www.link1.com #IDENTIFIER http://www.link2.org #IDENTIFIER http://www.link3.com #IDENTIFIER http://www.link4.net";

My objective is to extract each #IDENTIFIER link occurrence from this and I am doing it using the following code:

string pat = @"(#IDENTIFIER)(.*)\.(com|org|net)";
MatchCollection matches = Regex.Matches(text, pat);
foreach(Match match in matches) {
    Console.WriteLine("'{0}' found at index {1}.", match.Value, match.Index);
}

The problem is, it returns one match and not 4. Why are the in-between patterns ignored?

Do you know what I am missing?

Try `RegexOptions.RightToLeft`. That usually works when handling recurring prefixes. — Jesse de Wit, May 28 '17 at 19:48
@Lloyd is right, but if it's a multiline-problem use the m flag : https://msdn.microsoft.com/en-US/library/yd1hzczs(v=vs.110).aspx — jojomojo, May 28 '17 at 19:48

Lloyd · Answer 1 · 2017-05-28T19:49:14.840

1

It's because .* on its own is generally greedy. Instead try using .*?:

string pat = @"(#IDENTIFIER)(.*?)\.(com|org|net)";

edited May 28 '17 at 19:49

answered May 28 '17 at 19:47

Lloyd

29,197
4
84
98

I did, it worked. Thanks! – dspfnder May 28 '17 at 19:49
1

For an explanation: See https://stackoverflow.com/a/3075150/3883866 – Jesse de Wit May 28 '17 at 19:52

Regex.Matches Fails To Find Multiple Matches

1 Answers1