Question

I’m looking for a way of prepend any single digits in a string of integers and hyphens with 0. E.g.

“-0-2-3—12-0—10-” becomes “-00-02-03—12-00—10-“

or

“-12-14-7-8-” becomes “-12-13-07-08-“

I’ve tried using \d{1} with a combination of dashes but it doesn’t seem to capture all the correct parts. Any help would greatly appreciated. If a regex is too complex to do this do say, happen to write a traverser of some kind.

Thanks

Answer 1

If the regex engine supports lookaround assertions, then this is one way to do it:

s/(?<!\d)(?=\d(?!\d))/0/g

If the regex engine doesn’t support lookbehind assertions (e.g. JavaScript), then:

s/(^|[^\d])(?=\d(!\d))/$10/g

If the regex engine doesn’t support lookaround assertions at all, then:

s/(^|[^\d])(\d)([^\d])/$10$2$3/g