And as the Monks prefer, no grouping () to be seen.

Just to nail this point, I doubt anyone has good grounds to object to relevant use of grouping. The problem is that by default using brackets creates a capture group and this results in 2 levels of potential inefficiency (the group and the capture). And that's not to say that capture groups are bad - far from it. There is just no point in paying the performance penalty if you don't need the capturing.

The inefficiencies being discussed here are obviously small but if you are using such a regex in the middle of tight loop which runs millions/billions of times then these things mount up so it is as well to be aware of them. I wouldn't go tying myself in knots to avoid them in cases where they don't matter.

In general:

• If you have a need for capture groups, use them but be aware of the potential performance penalty
• If you have a need for groups but not capture, use them but ensure they are non-capturing using the methods already outlined by haukex
• If you don't have a need for groups, don't use them

We've all seen code where people have sprinkled unnecessary characters. In most cases it has no effect (good or bad) and just makes the code harder to read and maintain. With brackets in regex there is an effect and the price is worth paying if your code makes use of the functionality. But if you don't need it then it is best avoided.

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.