Need help in Regex Replace C#

Question

Is there a way that the Regex will check the first and the last character, but will replace only the IV and not the spaces.

Regex.Replace("This is IV item.", "[^A-Za-z0-9](IV)[^A-Za-z0-9]", "fourth");

Please don't tell me about MatchEvaluator and other Match based things, I need a one line solution, and one line doesn't mean combining code, it means using Replace method only.

Also I am not talking only about spaces, I am talking in general for any character, like: (

Once again, let me clear, I am not looking for anything other than some regex symbols that will match the characters but won't replace it and not this method:

Regex.Replace("This is IV item.", "([^A-Za-z0-9])(IV)([^A-Za-z0-9])", "$1fourth$3");

as this regex are parameters to some code that will automatically automatically uses $1 for some thing and I don't want to change that code, so is there a way so that $1 will be IV only, while checking that the previous character also.

If I may be so forward as to ask, why do you need a one-liner for this? — Rory
– Rory, Commented Jan 14, 2010 at 17:09
as already told the Regex Replace is in some other lib, which I don't want to modify. the Regex is input to that. So the question is about writing regex and not C# code. — Priyank Bolia
– Priyank Bolia, Commented Jan 14, 2010 at 17:13

Pent Ploompuu · Accepted Answer · 2010-01-14 17:14:10Z

5

Regex.Replace("This is IV item.", @"\bIV\b", "fourth");

answered Jan 14, 2010 at 17:14

Pent Ploompuu

5,4041 gold badge31 silver badges48 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Priyank Bolia Over a year ago

what about "This is !IV item." I said it can be any symbol.

Mark Byers Over a year ago

This works for "This is !IV item." It fails for "This is _IV_ item though."

Pent Ploompuu Over a year ago

The word boundary (\b) method is very simple and often all you need. If this isn't enough then you should use the look-behind/look-ahead solutions.

Mark Byers · Accepted Answer · 2010-01-14 17:19:44Z

2

It's not entirely clear from your question exactly what you want to accept and reject, but I think you need something like this:

Regex.Replace("This is IV item.", "(?<=[^A-Za-z0-9])(IV)(?=[^A-Za-z0-9])", "fourth");

answered Jan 14, 2010 at 17:19

Mark Byers

844k202 gold badges1.6k silver badges1.5k bronze badges

Comments

Jay Bazuzi · Accepted Answer · 2010-01-14 17:23:40Z

2

What you are looking for are so called look behinds and look aheads. Try using (?<=\ )IV(?!<=\ ) as a pattern.

edited Jan 14, 2010 at 17:23

Jay Bazuzi

46.9k17 gold badges117 silver badges173 bronze badges

answered Jan 14, 2010 at 17:08

Matthias

12.3k4 gold badges53 silver badges96 bronze badges

2 Comments

Priyank Bolia Over a year ago

+1 as is the what I was looking. Sorry, not accepting this cause I run into issues with the syntax given, so accepting the one with the example.

Alan Moore Over a year ago

I think you meant (?<=\ )IV(?=\ ). Anyway, the OP said the surrounding characters could be anything other than ASCII letters and digits, not just spaces.

Collectives™ on Stack Overflow

Need help in Regex Replace C#

3 Answers 3

3 Comments

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

3 Comments

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related