Writing a Replace Regex

Question

I need some help writing a regex. I have the following strings,

xxx.yyy.wwwwwaaa_IN_123                
xxx.rrrttttt_IN_12355                  
zz.iiiiolll_IN_12                         
xxx.zzzz.rrrr.yyy.wwwwwwww_IN_1232 

Using Regex.Replace, I want to change the string from the above format to something like

"$1($2)" where $2 would be the number at the end of the string and $1 would be the first three letters of the last substring before the _IN_ mark.

In another words,

xxx.yyy.wwwwwaaa_IN_123                www(123)
xxx.rrrttttt_IN_12355                  rrr(12355)
iiiiolll_IN_12                         iii(12)
xxx.zzzz.rrrr.yyy.wwwwwwww_IN_1232     www(1232)

This is what i have,

".*.([^\.]{3})[^\.]_IN_+([0-9]+)"

but this only takes the last letters before the _IN_ mark, and not the first letters of the last substring.

Thanks in advance

Answer 1

Well, the right regex is:

Regex r = new Regex("([a-z]{3})[a-z]*_IN_(\d+)");

You might need a RegexOptions.IgnoreCase in case there might be upper case letters. If you the regex is defined as a static member you might consider using RegexOptions.Compiled.

The above Regex will match bbb(123) in the string aaa_bbbbbb_IN_123.
The answer made by L.B would match aaa. The answer made by Frederik C will not match because there is no "." (like your 3rd example)

Answer 2

This does the trick, the non-greedy parts makes it not capture to much...

Regex.Match(input, @"(?:.*?\.)?(.{3})[^.]*?_IN_(\d+)");