A regular expression is a sequence of characters that define a search pattern, mainly for use in pattern matching with strings. Ruby regular expressions i.e. Ruby regex for short, helps us to find particular patterns inside a string. … Ruby regex expressions are declared between two forward slashes.

What regex engine does Ruby use?

EDIT: as pointed out in the comments the regex engine used by ruby is Onigmo which according to the linked to page has some of the new features of Perl 5.10. PCRE is a regex library and “The current implementation of PCRE corresponds approximately with Perl 5.12” so there may be some discrepancies around the edges.

What does *$ mean in regex?

*$ means – match, from beginning to end, any character that appears zero or more times. Basically, that means – match everything from start to end of the string. … Feel free to use an online tool like to test out regex patterns and strings.