I dont know whether using $& is effecient or not.

Using $& is not efficient, and usually to be avoided. See the entry in perlvar for details.

Update: perhaps I was a bit imprecise. I'd say something that "imposes a considerable performance penalty on all regular expression matches" is inefficient, but I guess it depends on what type of inefficiency we're talking about.

In reply to Re^2: 'grouping' substrings? by revdiablo
in thread 'grouping' substrings? by Anonymous Monk

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