Perl Compatible Regular Expressions

Perl Compatible Regular Expressions (PCRE) is a regular expression C library inspired by the regular expression capabilities in the Perl programming language, written by Philip Hazel, starting in summer 1997. PCRE's syntax is much more powerful and flexible than either of the POSIX regular expression flavors and many other regular expression libraries.

While PCRE originally aimed at feature-equivalence with Perl, the two implementations are not fully equivalent. During the PCRE 7.x and Perl 5.9.x phase, the two projects have coordinated development, with features being ported between them in both directions.

The PCRE library is incorporated into a number of prominent open source programs, such as the Apache HTTP Server and the PHP and R scripting languages; and can be incorporated in proprietary software too (BSD license). As of Perl 5.10, PCRE is also available as a replacement for Perl's default regular expression engine through the re::engine::PCRE module.