doc/html/pcre.html

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<head>
<title>pcre specification</title>
</head>
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
<h1>pcre man page</h1>
<p>
Return to the <a href="index.html">PCRE index page</a>.
</p>
<p>
This page is part of the PCRE HTML documentation. It was generated automatically
from the original man page. If there is any nonsense in it, please consult the
man page, in case the conversion went wrong.
<br>
<ul>
<li><a name="TOC1" href="#SEC1">INTRODUCTION</a>
<li><a name="TOC2" href="#SEC2">USER DOCUMENTATION</a>
<li><a name="TOC3" href="#SEC3">AUTHOR</a>
<li><a name="TOC4" href="#SEC4">REVISION</a>
</ul>
<br><a name="SEC1" href="#TOC1">INTRODUCTION</a><br>
<P>
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.
</P>
<P>
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.
</P>
<P>
The two libraries contain identical sets of functions, except that the names in
the 16-bit library start with <b>pcre16_</b> instead of <b>pcre_</b>. To avoid
over-complication and reduce the documentation maintenance load, most of the
documentation describes the 8-bit library, with the differences for the 16-bit
library described separately in the
<a href="pcre16.html"><b>pcre16</b></a>
page. References to functions or structures of the form <i>pcre[16]_xxx</i> 
should be read as meaning "<i>pcre_xxx</i> when using the 8-bit library and 
<i>pcre16_xxx</i> when using the 16-bit library".
</P>
<P>
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.
</P>
<P>
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
<a href="pcrematching.html"><b>pcrematching</b></a>
page.
</P>
<P>
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
<a href="pcrecpp.html"><b>pcrecpp</b></a>
page has details of this interface. Other people's contributions can be found
in the <i>Contrib</i> directory at the primary FTP site, which is:
<a href="ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre">ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre</a>
</P>
<P>
Details of exactly which Perl regular expression features are and are not
supported by PCRE are given in separate documents. See the
<a href="pcrepattern.html"><b>pcrepattern</b></a>
and
<a href="pcrecompat.html"><b>pcrecompat</b></a>
pages. There is a syntax summary in the
<a href="pcresyntax.html"><b>pcresyntax</b></a>
page.
</P>
<P>
Some features of PCRE can be included, excluded, or changed when the library is
built. The
<a href="pcre_config.html"><b>pcre_config()</b></a>
function makes it possible for a client to discover which features are
available. The features themselves are described in the
<a href="pcrebuild.html"><b>pcrebuild</b></a>
page. Documentation about building PCRE for various operating systems can be
found in the <b>README</b> and <b>NON-UNIX-USE</b> files in the source
distribution.
</P>
<P>
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.
</P>
<br><a name="SEC2" href="#TOC1">USER DOCUMENTATION</a><br>
<P>
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 <b>pcredemo</b> section, are concatenated, for ease
of searching. The sections are as follows:
<pre>
  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 <b>pcregrep</b> 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 <b>pcretest</b> testing command
  pcreunicode       discussion of Unicode and UTF-8/16 support
</pre>
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.
</P>
<br><a name="SEC3" href="#TOC1">AUTHOR</a><br>
<P>
Philip Hazel
<br>
University Computing Service
<br>
Cambridge CB2 3QH, England.
<br>
</P>
<P>
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.
</P>
<br><a name="SEC4" href="#TOC1">REVISION</a><br>
<P>
Last updated: 10 January 2012
<br>
Copyright &copy; 1997-2012 University of Cambridge.
<br>
<p>
Return to the <a href="index.html">PCRE index page</a>.
</p>
1	<html>
2	<head>
3	<title>pcre specification</title>
4	</head>
5	<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6	<h1>pcre man page</h1>
7	<p>
8	Return to the <a href="index.html">PCRE index page</a>.
9	</p>
10	<p>
11	This page is part of the PCRE HTML documentation. It was generated automatically
12	from the original man page. If there is any nonsense in it, please consult the
13	man page, in case the conversion went wrong.
14	<br>
15	<ul>
16	<li><a name="TOC1" href="#SEC1">INTRODUCTION</a>
17	<li><a name="TOC2" href="#SEC2">USER DOCUMENTATION</a>
18	<li><a name="TOC3" href="#SEC3">AUTHOR</a>
19	<li><a name="TOC4" href="#SEC4">REVISION</a>
20	</ul>
21	<br><a name="SEC1" href="#TOC1">INTRODUCTION</a><br>
22	<P>
23	The PCRE library is a set of functions that implement regular expression
24	pattern matching using the same syntax and semantics as Perl, with just a few
25	differences. Some features that appeared in Python and PCRE before they
26	appeared in Perl are also available using the Python syntax, there is some
27	support for one or two .NET and Oniguruma syntax items, and there is an option
28	for requesting some minor changes that give better JavaScript compatibility.
29	</P>
30	<P>
31	Starting with release 8.30, it is possible to compile two separate PCRE
32	libraries: the original, which supports 8-bit character strings (including
33	UTF-8 strings), and a second library that supports 16-bit character strings
34	(including UTF-16 strings). The build process allows either one or both to be
35	built. The majority of the work to make this possible was done by Zoltan
36	Herczeg.
37	</P>
38	<P>
39	The two libraries contain identical sets of functions, except that the names in
40	the 16-bit library start with <b>pcre16_</b> instead of <b>pcre_</b>. To avoid
41	over-complication and reduce the documentation maintenance load, most of the
42	documentation describes the 8-bit library, with the differences for the 16-bit
43	library described separately in the
44	<a href="pcre16.html"><b>pcre16</b></a>
45	page. References to functions or structures of the form <i>pcre[16]_xxx</i>
46	should be read as meaning "<i>pcre_xxx</i> when using the 8-bit library and
47	<i>pcre16_xxx</i> when using the 16-bit library".
48	</P>
49	<P>
50	The current implementation of PCRE corresponds approximately with Perl 5.12,
51	including support for UTF-8/16 encoded strings and Unicode general category
52	properties. However, UTF-8/16 and Unicode support has to be explicitly enabled;
53	it is not the default. The Unicode tables correspond to Unicode release 6.0.0.
54	</P>
55	<P>
56	In addition to the Perl-compatible matching function, PCRE contains an
57	alternative function that matches the same compiled patterns in a different
58	way. In certain circumstances, the alternative function has some advantages.
59	For a discussion of the two matching algorithms, see the
60	<a href="pcrematching.html"><b>pcrematching</b></a>
61	page.
62	</P>
63	<P>
64	PCRE is written in C and released as a C library. A number of people have
65	written wrappers and interfaces of various kinds. In particular, Google Inc.
66	have provided a comprehensive C++ wrapper for the 8-bit library. This is now
67	included as part of the PCRE distribution. The
68	<a href="pcrecpp.html"><b>pcrecpp</b></a>
69	page has details of this interface. Other people's contributions can be found
70	in the <i>Contrib</i> directory at the primary FTP site, which is:
71	<a href="ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre">ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre</a>
72	</P>
73	<P>
74	Details of exactly which Perl regular expression features are and are not
75	supported by PCRE are given in separate documents. See the
76	<a href="pcrepattern.html"><b>pcrepattern</b></a>
77	and
78	<a href="pcrecompat.html"><b>pcrecompat</b></a>
79	pages. There is a syntax summary in the
80	<a href="pcresyntax.html"><b>pcresyntax</b></a>
81	page.
82	</P>
83	<P>
84	Some features of PCRE can be included, excluded, or changed when the library is
85	built. The
86	<a href="pcre_config.html"><b>pcre_config()</b></a>
87	function makes it possible for a client to discover which features are
88	available. The features themselves are described in the
89	<a href="pcrebuild.html"><b>pcrebuild</b></a>
90	page. Documentation about building PCRE for various operating systems can be
91	found in the <b>README</b> and <b>NON-UNIX-USE</b> files in the source
92	distribution.
93	</P>
94	<P>
95	The libraries contains a number of undocumented internal functions and data
96	tables that are used by more than one of the exported external functions, but
97	which are not intended for use by external callers. Their names all begin with
98	"_pcre_" or "_pcre16_", which hopefully will not provoke any name clashes. In
99	some environments, it is possible to control which external symbols are
100	exported when a shared library is built, and in these cases the undocumented
101	symbols are not exported.
102	</P>
103	<br><a name="SEC2" href="#TOC1">USER DOCUMENTATION</a><br>
104	<P>
105	The user documentation for PCRE comprises a number of different sections. In
106	the "man" format, each of these is a separate "man page". In the HTML format,
107	each is a separate page, linked from the index page. In the plain text format,
108	all the sections, except the <b>pcredemo</b> section, are concatenated, for ease
109	of searching. The sections are as follows:
110	<pre>
111	pcre this document
112	pcre16 details of the 16-bit library
113	pcre-config show PCRE installation configuration information
114	pcreapi details of PCRE's native C API
115	pcrebuild options for building PCRE
116	pcrecallout details of the callout feature
117	pcrecompat discussion of Perl compatibility
118	pcrecpp details of the C++ wrapper for the 8-bit library
119	pcredemo a demonstration C program that uses PCRE
120	pcregrep description of the <b>pcregrep</b> command (8-bit only)
121	pcrejit discussion of the just-in-time optimization support
122	pcrelimits details of size and other limits
123	pcrematching discussion of the two matching algorithms
124	pcrepartial details of the partial matching facility
125	pcrepattern syntax and semantics of supported regular expressions
126	pcreperform discussion of performance issues
127	pcreposix the POSIX-compatible C API for the 8-bit library
128	pcreprecompile details of saving and re-using precompiled patterns
129	pcresample discussion of the pcredemo program
130	pcrestack discussion of stack usage
131	pcresyntax quick syntax reference
132	pcretest description of the <b>pcretest</b> testing command
133	pcreunicode discussion of Unicode and UTF-8/16 support
134	</pre>
135	In addition, in the "man" and HTML formats, there is a short page for each
136	8-bit C library function, listing its arguments and results.
137	</P>
138	<br><a name="SEC3" href="#TOC1">AUTHOR</a><br>
139	<P>
140	Philip Hazel
141	<br>
142	University Computing Service
143	<br>
144	Cambridge CB2 3QH, England.
145	<br>
146	</P>
147	<P>
148	Putting an actual email address here seems to have been a spam magnet, so I've
149	taken it away. If you want to email me, use my two initials, followed by the
150	two digits 10, at the domain cam.ac.uk.
151	</P>
152	<br><a name="SEC4" href="#TOC1">REVISION</a><br>
153	<P>
154	Last updated: 10 January 2012
155	<br>
156	Copyright © 1997-2012 University of Cambridge.
157	<br>
158	<p>
159	Return to the <a href="index.html">PCRE index page</a>.
160	</p>
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