Matching plurals using regex in C#

Question

I'm looking to use regex in C# to search for terms and I want to include the plurals of those terms in the search. For example if the user wants to search for 'pipe' then I want to return results for 'pipes' as well.

So I can do this...

string s ="\\b" + term + "s*\\b";
if (Regex.IsMatch(bigtext, s) {  /* do stuff */ }

How would I modify the above to allow me to match, say, 'stresses' when the user enters 'stress' and still work for 'pipe'/'pipes'?

Answer 1

The problem you can face is that there are a lot of irregular nouns such as man, fish and index. So you should consider using the PluralizationService that has a Pluralize method. Here is an example that shows how to use it.

After you get the plural of the term, you can easily construct a regex that searches for both the plural or the singular term.

PluralizationService ps = PluralizationService.CreateService(CultureInfo.CurrentCulture);
string plural = ps.Pluralize(term);
string s = @"("+term+"|"+plural+")";
if (Regex.IsMatch(bigtext, s)) {
    /* do stuff */
}

Answer 2

Here's a regex created to remove the plurals:

 /(?<![aei])([ie][d])(?=[^a-zA-Z])|(?<=[ertkgwmnl])s(?=[^a-zA-Z])/g

(Demo & source)

I know it's not exactly what you need, but it may help you find something out.