in reply to Re^4: Defining Characters in Word Boundary?
in thread Defining Characters in Word Boundary?

(?<![a-zA-Z]) emulates \b at the beginning of an alphabetic string and (?![a-zA-Z]) emulates \b at the end of an alphabetic string.

But as I explained before, it doesn't seem from iaw4's problem description that asserting a boundary match is even needed.

UPDATE: Removed color.

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Re^6: Defining Characters in Word Boundary?
by ikegami (Patriarch) on Jan 21, 2011 at 01:24 UTC
    Needed? Not likely. But conceptually, (?![a-zA-Z]) is simpler. With it, we're defining the macro without requiring the presence of some external context.
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