Regular expression functionality in Qore is provided by PCRE: Perl-Compatible Regular Expression library.

Using this library, Qore implements regular expression pattern matching using the same syntax and semantics as Perl 5.

The following is a list of operators based on regular expressions (or similar to regular expressions in the case of the transliteration operator).

Regular Expression Operators

Operator	Description
Regular Expression Match Operator (=~)	Returns True if the regular expression matches a string
Regular Expression No Match Operator (!~)	Returns True if the regular expression does not match a string
Regular Expression Substitution Operator	Substitutes text in a string based on matching a regular expression
Regular Expression Pattern Extraction Operator	Returns a list of substrings in a string based on matching patterns defined by a regular expression
Transliteration Operator	Not a regular expression operator; transliterates one or more characters to other characters in a string

See the table below for valid regular expression options.

Regular Expression Options

Option	Description
`i`	Ignores case when matching
`m`	makes start-of-line (`^`) or end-of-line (`$`) match after or before any newline in the subject string
`s`	makes a dot (`.`) match a newline character
`x`	ignores whitespace characters and enables comments prefixed by `#`
`g`	makes global substitutions or global extractions (only applicable with the substitution and extraction operators)

The following is a list of functions providing regular expression functionality where the pattern may be given at run-time:

Regular Expression Functions

Function	Description
regex()	Returns True if the regular expression matches a string
regex_subst()	Substitutes a pattern in a string based on regular expressions and returns the new string
regex_extract()	Returns a list of substrings in a string based on matching patterns defined by a regular expression