When not to use Regex in C# (or Java, C++, etc.)

It is clear that there are lots of problems that look like a simple regex expression will solve, but which prove to be very hard to solve with regex.

So how does someone that is not an expert in regex, know if he/she should be learning regex to solve a given problem?

(See "Regex to parse C# source code to find all strings" for way I am asking this question.)

This seems to sums it up well:

Some people, when confronted with a problem, think “I know, I'll use regular expressions.” Now they have two problems...

(I have just changed the title of the question to make it more specific, as some of the problems with Regex in C# are solved in Perl and JScript, for example the fact that the two levels of quoting makes a Regex so unreadable.)

c# java regex

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The main concern here is maintainability.

It is obvious to me, that any programmer worth his salt must know regular expressions. Not knowing them is like, say, not knowing what abstraction and encapsulation is, only, probably, worse. So this is out of the question.

On the other hand, one should consider, that maintiaining regex-driven code (written in any language) can be a nightmare even for someone who is really good at them. So, in my opinion, the correct approach here is to only use them when it is inevitable and when the code using regex' will be more readable than its non-regex variant. And, of course, as has been already indicated, do not use them for something, that they are not meant to do (like xml). And no email address validation either (one of my pet peeves :P)!

But seriously, doesn't it feel wrong when you use all those substrs for something, that can be solved with a handful of characters, looking like line noise? I know it did for me.

answered 2009-06-09T10:24:27.720

When not to use Regex in C# (or Java, C++, etc.)

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