This regex matches roman numbers from 1 (I) to 3999 (MMMCMXCIX)

matches only those commas that are between sets, or between members of a set. does not match commas that are inside members.

Validates Multiple email addresses seperated by comma.

Awesome explanation of nested lookbacks

Validating comma delimited strings for whitespaces & extra commas -- +(,()+){0,}

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Full email validation with optional "." "-" "_"

An extremely complete regex, that... Accepts international phones and most of regional phone numbers; Accepts phone numbers with/without "+", with/without space or "-" in the middle of the phone, and more. Gets groups of all important data of the phone number (local code, country code and the phone ...

For string splitting / deconstructing

By inserting this regex in a programming language to test it against Codeforces 1800A you'll solve the task

style img

Using the twitter API, take a tweet object and find & link #tags to embed in HTML

Capture alternative items matching end of lines country codes