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revision 75 by nigel, Sat Feb 24 21:40:37 2007 UTC revision 77 by nigel, Sat Feb 24 21:40:45 2007 UTC
# Line 23  man page, in case the conversion went wr Line 23  man page, in case the conversion went wr
23  <P>  <P>
24  The PCRE library is a set of functions that implement regular expression  The PCRE library is a set of functions that implement regular expression
25  pattern matching using the same syntax and semantics as Perl, with just a few  pattern matching using the same syntax and semantics as Perl, with just a few
26  differences. The current implementation of PCRE (release 5.x) corresponds  differences. The current implementation of PCRE (release 6.x) corresponds
27  approximately with Perl 5.8, including support for UTF-8 encoded strings and  approximately with Perl 5.8, including support for UTF-8 encoded strings and
28  Unicode general category properties. However, this support has to be explicitly  Unicode general category properties. However, this support has to be explicitly
29  enabled; it is not the default.  enabled; it is not the default.
30  </P>  </P>
31  <P>  <P>
32    In addition to the Perl-compatible matching function, PCRE also contains an
33    alternative matching function that matches the same compiled patterns in a
34    different way. In certain circumstances, the alternative function has some
35    advantages. For a discussion of the two matching algorithms, see the
36    <a href="pcrematching.html"><b>pcrematching</b></a>
37    page.
38    </P>
39    <P>
40  PCRE is written in C and released as a C library. A number of people have  PCRE is written in C and released as a C library. A number of people have
41  written wrappers and interfaces of various kinds. A C++ class is included in  written wrappers and interfaces of various kinds. In particular, Google Inc.
42  these contributions, which can be found in the <i>Contrib</i> directory at the  have provided a comprehensive C++ wrapper. This is now included as part of the
43  primary FTP site, which is:  PCRE distribution. The
44    <a href="pcrecpp.html"><b>pcrecpp</b></a>
45    page has details of this interface. Other people's contributions can be found
46    in the <i>Contrib</i> directory at the primary FTP site, which is:
47  <a href="ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre">ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre</a>  <a href="ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre">ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre</a>
48  </P>  </P>
49  <P>  <P>
# Line 53  available. The features themselves are d Line 64  available. The features themselves are d
64  page. Documentation about building PCRE for various operating systems can be  page. Documentation about building PCRE for various operating systems can be
65  found in the <b>README</b> file in the source distribution.  found in the <b>README</b> file in the source distribution.
66  </P>  </P>
67    <P>
68    The library contains a number of undocumented internal functions and data
69    tables that are used by more than one of the exported external functions, but
70    which are not intended for use by external callers. Their names all begin with
71    "_pcre_", which hopefully will not provoke any name clashes.
72    </P>
73  <br><a name="SEC2" href="#TOC1">USER DOCUMENTATION</a><br>  <br><a name="SEC2" href="#TOC1">USER DOCUMENTATION</a><br>
74  <P>  <P>
75  The user documentation for PCRE comprises a number of different sections. In  The user documentation for PCRE comprises a number of different sections. In
# Line 62  all the sections are concatenated, for e Line 79  all the sections are concatenated, for e
79  follows:  follows:
80  <pre>  <pre>
81    pcre              this document    pcre              this document
82    pcreapi           details of PCRE's native API    pcreapi           details of PCRE's native C API
83    pcrebuild         options for building PCRE    pcrebuild         options for building PCRE
84    pcrecallout       details of the callout feature    pcrecallout       details of the callout feature
85    pcrecompat        discussion of Perl compatibility    pcrecompat        discussion of Perl compatibility
86      pcrecpp           details of the C++ wrapper
87    pcregrep          description of the <b>pcregrep</b> command    pcregrep          description of the <b>pcregrep</b> command
88      pcrematching      discussion of the two matching algorithms
89    pcrepartial       details of the partial matching facility    pcrepartial       details of the partial matching facility
90    pcrepattern       syntax and semantics of supported regular expressions    pcrepattern       syntax and semantics of supported regular expressions
91    pcreperform       discussion of performance issues    pcreperform       discussion of performance issues
92    pcreposix         the POSIX-compatible API    pcreposix         the POSIX-compatible C API
93    pcreprecompile    details of saving and re-using precompiled patterns    pcreprecompile    details of saving and re-using precompiled patterns
94    pcresample        discussion of the sample program    pcresample        discussion of the sample program
95    pcretest          description of the <b>pcretest</b> testing command    pcretest          description of the <b>pcretest</b> testing command
96  </pre>  </pre>
97  In addition, in the "man" and HTML formats, there is a short page for each  In addition, in the "man" and HTML formats, there is a short page for each
98  library function, listing its arguments and results.  C library function, listing its arguments and results.
99  </P>  </P>
100  <br><a name="SEC3" href="#TOC1">LIMITATIONS</a><br>  <br><a name="SEC3" href="#TOC1">LIMITATIONS</a><br>
101  <P>  <P>
# Line 104  subpatterns, assertions, and other types Line 123  subpatterns, assertions, and other types
123  </P>  </P>
124  <P>  <P>
125  The maximum length of a subject string is the largest positive number that an  The maximum length of a subject string is the largest positive number that an
126  integer variable can hold. However, PCRE uses recursion to handle subpatterns  integer variable can hold. However, when using the traditional matching
127  and indefinite repetition. This means that the available stack space may limit  function, PCRE uses recursion to handle subpatterns and indefinite repetition.
128  the size of a subject string that can be processed by certain patterns.  This means that the available stack space may limit the size of a subject
129    string that can be processed by certain patterns.
130  <a name="utf8support"></a></P>  <a name="utf8support"></a></P>
131  <br><a name="SEC4" href="#TOC1">UTF-8 AND UNICODE PROPERTY SUPPORT</a><br>  <br><a name="SEC4" href="#TOC1">UTF-8 AND UNICODE PROPERTY SUPPORT</a><br>
132  <P>  <P>
# Line 174  bytes, for example: \x{100}{3}. Line 194  bytes, for example: \x{100}{3}.
194  </P>  </P>
195  <P>  <P>
196  6. The escape sequence \C can be used to match a single byte in UTF-8 mode,  6. The escape sequence \C can be used to match a single byte in UTF-8 mode,
197  but its use can lead to some strange effects.  but its use can lead to some strange effects. This facility is not available in
198    the alternative matching function, <b>pcre_dfa_exec()</b>.
199  </P>  </P>
200  <P>  <P>
201  7. The character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly  7. The character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly
# Line 199  values. Line 220  values.
220  </P>  </P>
221  <br><a name="SEC5" href="#TOC1">AUTHOR</a><br>  <br><a name="SEC5" href="#TOC1">AUTHOR</a><br>
222  <P>  <P>
223  Philip Hazel &#60;ph10@cam.ac.uk&#62;  Philip Hazel
224  <br>  <br>
225  University Computing Service,  University Computing Service,
226  <br>  <br>
227  Cambridge CB2 3QG, England.  Cambridge CB2 3QG, England.
228    </P>
229    <P>
230    Putting an actual email address here seems to have been a spam magnet, so I've
231    taken it away. If you want to email me, use my initial and surname, separated
232    by a dot, at the domain ucs.cam.ac.uk.
233    Last updated: 07 March 2005
234  <br>  <br>
235  Phone: +44 1223 334714  Copyright &copy; 1997-2005 University of Cambridge.
 Last updated: 09 September 2004  
 <br>  
 Copyright &copy; 1997-2004 University of Cambridge.  
236  <p>  <p>
237  Return to the <a href="index.html">PCRE index page</a>.  Return to the <a href="index.html">PCRE index page</a>.
238  </p>  </p>

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