Regular expression for fractional street address

Question

I am trying to write a regular expression to match the fractional portion of a street address (e.g. 123 1/2 Broadway). This is what I have:

(?<=\d+ )\d/\d

So basically match any string x/x that follows any number of digits and a space. For some reason I don't get any matches. If I remove the plus this works okay:

(?<=\d )\d/\d

... but I still don't understand why the first one wouldn't work. Thanks!

Which regex engine are you using? Some of them don't support variable length look-behinds. — Rohit Jain, Aug 08 '13 at 20:20
Yes, please be more explicit about context. RegEx engine, programming language / command line utility. Code segment in the first case, exact command and options in the second, etc. — Mario Rossi, Aug 08 '13 at 20:27
Sorry about that - this will be in JavaScript but at the moment I'm just using the search function in Sublime Text to test it out. — serverpunk, Aug 08 '13 at 20:36

score 2 · Accepted Answer · edited May 23 '17 at 11:56

2

Depending on your regex engine, the characters in your lookbehind have to be of fixed width. Since \d+ is not fixed width (+ means it can be 1, 2, 3, etc times), it won't work.

As for why, I think that this answer answers it well :)

edited May 23 '17 at 11:56

Community

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answered Aug 08 '13 at 20:21

Jerry

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Regular expression for fractional street address

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