pcresample(3) [x11r4 man page]
PCRESAMPLE(3) Library Functions Manual PCRESAMPLE(3) NAME
PCRE - Perl-compatible regular expressions PCRE SAMPLE PROGRAM
A simple, complete demonstration program, to get you started with using PCRE, is supplied in the file pcredemo.c in the PCRE distribution. The program compiles the regular expression that is its first argument, and matches it against the subject string in its second argument. No PCRE options are set, and default character tables are used. If matching succeeds, the program outputs the portion of the subject that matched, together with the contents of any captured substrings. If the -g option is given on the command line, the program then goes on to check for further matches of the same regular expression in the same subject string. The logic is a little bit tricky because of the possibility of matching an empty string. Comments in the code explain what is going on. If PCRE is installed in the standard include and library directories for your system, you should be able to compile the demonstration pro- gram using this command: gcc -o pcredemo pcredemo.c -lpcre If PCRE is installed elsewhere, you may need to add additional options to the command line. For example, on a Unix-like system that has PCRE installed in /usr/local, you can compile the demonstration program using a command like this: gcc -o pcredemo -I/usr/local/include pcredemo.c -L/usr/local/lib -lpcre Once you have compiled the demonstration program, you can run simple tests like this: ./pcredemo 'cat|dog' 'the cat sat on the mat' ./pcredemo -g 'cat|dog' 'the dog sat on the cat' Note that there is a much more comprehensive test program, called pcretest, which supports many more facilities for testing regular expres- sions and the PCRE library. The pcredemo program is provided as a simple coding example. On some operating systems (e.g. Solaris), when PCRE is not installed in the standard library directory, you may get an error like this when you try to run pcredemo: ld.so.1: a.out: fatal: libpcre.so.0: open failed: No such file or directory This is caused by the way shared library support works on those systems. You need to add -R/usr/local/lib (for example) to the compile command to get round this problem. AUTHOR
Philip Hazel University Computing Service Cambridge CB2 3QH, England. REVISION
Last updated: 23 January 2008 Copyright (c) 1997-2008 University of Cambridge. PCRESAMPLE(3)
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PCRE(3) Library Functions Manual PCRE(3) NAME
PCRE - Perl-compatible regular expressions INTRODUCTION
The PCRE library is a set of functions that implement regular expression pattern matching using the same syntax and semantics as Perl, with just a few differences. Some features that appeared in Python and PCRE before they appeared in Perl are also available using the Python syntax, there is some support for one or two .NET and Oniguruma syntax items, and there is an option for requesting some minor changes that give better JavaScript compatibility. Starting with release 8.30, it is possible to compile two separate PCRE libraries: the original, which supports 8-bit character strings (including UTF-8 strings), and a second library that supports 16-bit character strings (including UTF-16 strings). The build process allows either one or both to be built. The majority of the work to make this possible was done by Zoltan Herczeg. The two libraries contain identical sets of functions, except that the names in the 16-bit library start with pcre16_ instead of pcre_. To avoid over-complication and reduce the documentation maintenance load, most of the documentation describes the 8-bit library, with the dif- ferences for the 16-bit library described separately in the pcre16 page. References to functions or structures of the form pcre[16]_xxx should be read as meaning "pcre_xxx when using the 8-bit library and pcre16_xxx when using the 16-bit library". The current implementation of PCRE corresponds approximately with Perl 5.12, including support for UTF-8/16 encoded strings and Unicode general category properties. However, UTF-8/16 and Unicode support has to be explicitly enabled; it is not the default. The Unicode tables correspond to Unicode release 6.0.0. In addition to the Perl-compatible matching function, PCRE contains an alternative function that matches the same compiled patterns in a different way. In certain circumstances, the alternative function has some advantages. For a discussion of the two matching algorithms, see the pcrematching page. PCRE is written in C and released as a C library. A number of people have written wrappers and interfaces of various kinds. In particular, Google Inc. have provided a comprehensive C++ wrapper for the 8-bit library. This is now included as part of the PCRE distribution. The pcrecpp page has details of this interface. Other people's contributions can be found in the Contrib directory at the primary FTP site, which is: ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre Details of exactly which Perl regular expression features are and are not supported by PCRE are given in separate documents. See the pcrepattern and pcrecompat pages. There is a syntax summary in the pcresyntax page. Some features of PCRE can be included, excluded, or changed when the library is built. The pcre_config() function makes it possible for a client to discover which features are available. The features themselves are described in the pcrebuild page. Documentation about building PCRE for various operating systems can be found in the README and NON-UNIX-USE files in the source distribution. The libraries contains a number of undocumented internal functions and data tables that are used by more than one of the exported external functions, but which are not intended for use by external callers. Their names all begin with "_pcre_" or "_pcre16_", which hopefully will not provoke any name clashes. In some environments, it is possible to control which external symbols are exported when a shared library is built, and in these cases the undocumented symbols are not exported. USER DOCUMENTATION
The user documentation for PCRE comprises a number of different sections. In the "man" format, each of these is a separate "man page". In the HTML format, each is a separate page, linked from the index page. In the plain text format, all the sections, except the pcredemo sec- tion, are concatenated, for ease of searching. The sections are as follows: pcre this document pcre16 details of the 16-bit library pcre-config show PCRE installation configuration information pcreapi details of PCRE's native C API pcrebuild options for building PCRE pcrecallout details of the callout feature pcrecompat discussion of Perl compatibility pcrecpp details of the C++ wrapper for the 8-bit library pcredemo a demonstration C program that uses PCRE pcregrep description of the pcregrep command (8-bit only) pcrejit discussion of the just-in-time optimization support pcrelimits details of size and other limits pcrematching discussion of the two matching algorithms pcrepartial details of the partial matching facility pcrepattern syntax and semantics of supported regular expressions pcreperform discussion of performance issues pcreposix the POSIX-compatible C API for the 8-bit library pcreprecompile details of saving and re-using precompiled patterns pcresample discussion of the pcredemo program pcrestack discussion of stack usage pcresyntax quick syntax reference pcretest description of the pcretest testing command pcreunicode discussion of Unicode and UTF-8/16 support In addition, in the "man" and HTML formats, there is a short page for each 8-bit C library function, listing its arguments and results. AUTHOR
Philip Hazel University Computing Service Cambridge CB2 3QH, England. Putting an actual email address here seems to have been a spam magnet, so I've taken it away. If you want to email me, use my two initials, followed by the two digits 10, at the domain cam.ac.uk. REVISION
Last updated: 10 January 2012 Copyright (c) 1997-2012 University of Cambridge. PCRE(3)