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Perl Compatible Regular Expressions (PCRE) is a library written in C, which implements a regular expression engine, inspired by the capabilities of the Perl programming language. Philip Hazel started writing PCRE in summer 1997. [ 3 ]
Standard library includes PCRE-based Regex module. The matching algorithms of the library are based on the PCRE library, but not all of the PCRE library is interfaced and some parts of the library go beyond what PCRE offers. Currently PCRE version 8.40 (release date 2017-01-11) is used. Erlang: erlang.org: Apache 2.0
A regular expression (shortened as regex or regexp), [1] sometimes referred to as rational expression, [2] [3] is a sequence of characters that specifies a match pattern in text. Usually such patterns are used by string-searching algorithms for "find" or "find and replace" operations on strings , or for input validation .
For certain regular expression operators like | (the operator for alternation or logical disjunction) it is superior to PCRE. Unlike PCRE, which supports features such as lookarounds, backreferences and recursion , RE2 is only able to recognize regular languages due to its construction using the Thompson DFA [ 4 ] algorithm.
PCRE Perl Compatible Regular Expressions, a common modern implementation of string pattern matching ported to many languages; REBOL parse dialect for pattern matching used to implement language dialects; Symbolic integration; Tagged union; Tom (pattern matching language) SNOBOL for a programming language based on one kind of pattern matching
Here is a very simple program in re2c (example.re). It checks that all input arguments are hexadecimal numbers. The code for re2c is enclosed in comments /*!re2c ... */, all the rest is plain C code. See the official re2c website for more complex examples. [23]
A regular expression denial of service ... For example, if you try to match ... (WAF) was brought down by a PCRE ReDoS in 2019, ...
A metacharacter is a character that has a special meaning to a computer program, such as a shell interpreter or a regular expression (regex) engine.. In POSIX extended regular expressions, there are 14 metacharacters that must be escaped — preceded by a backslash (\) — in order to drop their special meaning and be treated literally inside an expression: opening and closing square brackets ...