100 lines
3.3 KiB
Groff
100 lines
3.3 KiB
Groff
.TH PCRE2SAMPLE 3 "02 February 2016" "PCRE2 10.22"
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.SH NAME
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PCRE2 - Perl-compatible regular expressions (revised API)
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.SH "PCRE2 SAMPLE PROGRAM"
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.rs
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.sp
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A simple, complete demonstration program to get you started with using PCRE2 is
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supplied in the file \fIpcre2demo.c\fP in the \fBsrc\fP directory in the PCRE2
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distribution. A listing of this program is given in the
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.\" HREF
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\fBpcre2demo\fP
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.\"
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documentation. If you do not have a copy of the PCRE2 distribution, you can
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save this listing to re-create the contents of \fIpcre2demo.c\fP.
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.P
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The demonstration program compiles the regular expression that is its
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first argument, and matches it against the subject string in its second
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argument. No PCRE2 options are set, and default character tables are used. If
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matching succeeds, the program outputs the portion of the subject that matched,
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together with the contents of any captured substrings.
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.P
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If the -g option is given on the command line, the program then goes on to
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check for further matches of the same regular expression in the same subject
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string. The logic is a little bit tricky because of the possibility of matching
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an empty string. Comments in the code explain what is going on.
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.P
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The code in \fBpcre2demo.c\fP is an 8-bit program that uses the PCRE2 8-bit
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library. It handles strings and characters that are stored in 8-bit code units.
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By default, one character corresponds to one code unit, but if the pattern
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starts with "(*UTF)", both it and the subject are treated as UTF-8 strings,
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where characters may occupy multiple code units.
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.P
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If PCRE2 is installed in the standard include and library directories for your
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operating system, you should be able to compile the demonstration program using
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a command like this:
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.sp
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cc -o pcre2demo pcre2demo.c -lpcre2-8
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.sp
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If PCRE2 is installed elsewhere, you may need to add additional options to the
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command line. For example, on a Unix-like system that has PCRE2 installed in
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\fI/usr/local\fP, you can compile the demonstration program using a command
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like this:
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.sp
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.\" JOINSH
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cc -o pcre2demo -I/usr/local/include pcre2demo.c \e
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-L/usr/local/lib -lpcre2-8
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.sp
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Once you have built the demonstration program, you can run simple tests like
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this:
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.sp
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./pcre2demo 'cat|dog' 'the cat sat on the mat'
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./pcre2demo -g 'cat|dog' 'the dog sat on the cat'
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.sp
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Note that there is a much more comprehensive test program, called
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.\" HREF
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\fBpcre2test\fP,
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.\"
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which supports many more facilities for testing regular expressions using all
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three PCRE2 libraries (8-bit, 16-bit, and 32-bit, though not all three need be
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installed). The
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.\" HREF
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\fBpcre2demo\fP
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.\"
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program is provided as a relatively simple coding example.
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.P
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If you try to run
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.\" HREF
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\fBpcre2demo\fP
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.\"
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when PCRE2 is not installed in the standard library directory, you may get an
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error like this on some operating systems (e.g. Solaris):
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.sp
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ld.so.1: pcre2demo: fatal: libpcre2-8.so.0: open failed: No such file or directory
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.sp
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This is caused by the way shared library support works on those systems. You
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need to add
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.sp
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-R/usr/local/lib
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.sp
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(for example) to the compile command to get round this problem.
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.
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.
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.SH AUTHOR
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.rs
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.sp
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.nf
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Philip Hazel
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University Computing Service
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Cambridge, England.
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.fi
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.
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.
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.SH REVISION
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.rs
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.sp
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.nf
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Last updated: 02 February 2016
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Copyright (c) 1997-2016 University of Cambridge.
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.fi
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