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This must be an easy one, but I am trying to detect if the integers 28, 81, 379 or 380 exist in a string.

I was using this pattern:

    pattern = /28|81|379|380/

But it also returns true for 381. So I need a modifier to make sure it is only looking for 81 specifically, and not 81 within a longer number. I know about the ^ and $ modifiers to check for the start and end, but I can't seem to figure out how to work those in to a pattern that is using the | symbol to check alternatives.

Regex is not my strength - hope you can help! - Dan

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2 Answers 2

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You can use something like:

/\b(?:28|81|379|380)\b/

With \b matching at a "word barrier", so these numbers will not match if they are part of a word/other numbers.

If you want to match 28 in foo28 (part of a "word") then you can use:

/(?:^|\D)(?:28|81|379|380)(?:\D|$)/

\D matches a not-number character.

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2 Comments

Thanks QTax! What does the ?: do?
@Dan Baylis that signifies a non-capturing group (meaning the group will not be available as a backreference)
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\b signifies a word boundary. You might use it as such:

/\b28\b|\b81\b|\b379\b|\b380\b/

Or as such:

/\b(28|81|379|380)\b/
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@Dan Baylis Good to hear. If you aren't using the value, it might be worth it to make it a non-capturing group as in Qtax's example.

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