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codes image If the question: Will the regular expression "?!:" What does that mean?

kai zhou
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2 Answers2

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This is a "Negative Lookahead Assertion". This code is saying "this regular expression matches only if it begins with /wiki/ and is not followed by a colon".

Consider reading through https://www.regular-expressions.info and in particular the Lookahead and Lookbehind Zero-Length Assertions.

hunteke
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? --> zero or one occurrences of the previous expression
! --> negation
: --> simple colon

So... it would mean 'zero or one occurrences of the previous expression, not followed by a colon'

D Ie
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