I have the following regex:
/#([A-Za-z0-9_]+)/g
How can I make it so that there must be a space before the hashtag for the regex to be valid (i.e. the second line in the link above shouldn't match).
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3 Answers
2
From:
/#([A-Za-z0-9_]+)/
To:
/\s#([A-Za-z0-9_]+)/
More information on matching space/s: Matching a space in regex
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Okay, how do I make it not include the space though? – Jul 02 '14 at 02:44
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1@user3769178: Well the hash-tag part is between brackets, you can use regex capturing techniques for this. Every programming language has some kind of api for this (but you didn't specify your environment). – Willem Van Onsem Jul 02 '14 at 02:46
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You can simply add a space in your regex as follows:
/ #([A-Za-z0-9_]+)/g
To not include the space in the match, you can do:
/(?:\s)(#[A-Za-z0-9_]+)/g
sshashank124
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@user3769178, Answer updated (second regex). Now if you use that regex, the ___first captured group___ will not contain the space. – sshashank124 Jul 02 '14 at 02:50
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Use \K or look behind to not to include space at the end result.
/ \K#([A-Za-z0-9_]+)/g
OR
(?<=\s)#([A-Za-z0-9_]+)
First captured group contains the string test. If you want the captured group to contain #, the use this regex (?<=\s)(#[A-Za-z0-9_]+)
Avinash Raj
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Why would this make any difference? Your regex matches strictly the same set of strings. Since the space is optional at the beginning, the regex can simply ignore this. – Willem Van Onsem Jul 02 '14 at 02:43
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looks like support may be an issue using `\K` ... http://stackoverflow.com/questions/13542950/support-of-k-in-regex – Alex Jul 02 '14 at 02:49
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