How can I use regex to match a character (') when not following a specific character (?)?

Question

How can I write a regex pattern to split a string by a specific delimiter as long as it's not preceded by a question mark?

I've written a parser that splits an EDIFACT message into segments, composites and elements. But in the EDI standard the question mark is an escape character. So to split this string:

'PRI+2.005:1+9022.5'RAD+RRHANB97+120814'

I can use string.Split('\''), and then string.split('+') and then string.split(':') to get PRI, 2.005, 1, 9022.5 and so on However, these characters can be escaped by a question mark:

'PRI+2.005?+3.2:1+9022.5'RAD?'R+RRHANB97+120814'

which should now be PRI, 2.005+3.2, 1, 9022.5, RAD'R, RRHANB97.

Can someone help with a regular expression that would match the ' and not the ?'?

Thanks

You could use a negative lookbehind: `(?<!\?)'` – Asad Saeeduddin Oct 19 '12 at 08:55 — Asad Saeeduddin, Oct 19 '12 at 08:55

score 6 · Accepted Answer · edited Oct 19 '12 at 08:59

6

With negative lookbehind:

(?<!\?)'

edited Oct 19 '12 at 08:59

answered Oct 19 '12 at 08:55

spender

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Thanks! I kept using (?=!\?)' Positive look ahead. – reckface Oct 19 '12 at 09:12

score 0 · Answer 2 · edited Feb 03 '16 at 09:50

0

Just use \' and instead of trying to do a regex.Matches, do a regex.Split instead

edited Feb 03 '16 at 09:50

ρяσѕρєя K

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answered Feb 03 '16 at 09:46

Tony Danby

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How can I use regex to match a character (') when not following a specific character (?)?

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