regex

javascript regex – look behind alternative?

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EDIT: From ECMAScript 2018 onwards, lookbehind assertions (even unbounded) are supported natively. In previous versions, you can do this: ^(?:(?!filename\.js$).)*\.js$ This does explicitly what the lookbehind expression is doing implicitly: check each character of the string if the lookbehind expression plus the regex after it will not match, and only then allow that character to … Read more

Replace specific characters within strings

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With a regular expression and the function gsub(): group <- c(“12357e”, “12575e”, “197e18”, “e18947”) group [1] “12357e” “12575e” “197e18” “e18947” gsub(“e”, “”, group) [1] “12357” “12575” “19718” “18947” What gsub does here is to replace each occurrence of “e” with an empty string “”. See ?regexp or gsub for more help.

Unicode equivalents for \w and \b in Java regular expressions?

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Source code The source code for the rewriting functions I discuss below is available here. Update in Java 7 Sun’s updated Pattern class for JDK7 has a marvelous new flag, UNICODE_CHARACTER_CLASS, which makes everything work right again. It’s available as an embeddable (?U) for inside the pattern, so you can use it with the String … Read more

Regex – How to match all brackets that are not inside quotes

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https://regex101.com/r/QAmbym/1 ^(?>”.*”|[^!{}])*\K!{.*} ^ – Anchor to the start of the string. This is important because of what’s next. (?> – atomic group. once matched, don’t backtrack. “.*” – Consume anything in quotes. Once consumed, the engine won’t backtrack for it | – or [^!{}] – match anything that isn’t the characters we’re interested in. These … Read more

Reference – What does this regex mean?

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The Stack Overflow Regular Expressions FAQ See also a lot of general hints and useful links at the regex tag details page. Online tutorials RegexOne ↪ Regular Expressions Info ↪ Quantifiers Zero-or-more: *:greedy, *?:reluctant, *+:possessive One-or-more: +:greedy, +?:reluctant, ++:possessive ?:optional (zero-or-one) Min/max ranges (all inclusive): {n,m}:between n & m, {n,}:n-or-more, {n}:exactly n Differences between greedy, … Read more