.TH PCRESAMPLE 3
.SH NAME
PCRE - Perl-compatible regular expressions
.SH "PCRE SAMPLE PROGRAM"
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A simple, complete demonstration program, to get you started with using PCRE,
is supplied in the file \fIpcredemo.c\fP in the PCRE distribution.
.P
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.
.P
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.
.P
The demonstration program is automatically built if you use "./configure;make"
to build PCRE. Otherwise, if PCRE is installed in the standard include and
library directories for your system, you should be able to compile the
demonstration program using this command:
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  gcc -o pcredemo pcredemo.c -lpcre
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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
\fI/usr/local\fP, you can compile the demonstration program using a command
like this:
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.\" JOINSH
  gcc -o pcredemo -I/usr/local/include pcredemo.c \e
      -L/usr/local/lib -lpcre
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Once you have compiled the demonstration program, you can run simple tests like
this:
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  ./pcredemo 'cat|dog' 'the cat sat on the mat'
  ./pcredemo -g 'cat|dog' 'the dog sat on the cat'
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Note that there is a much more comprehensive test program, called
.\" HREF
\fBpcretest\fP,
.\"
which supports many more facilities for testing regular expressions and the
PCRE library. The \fBpcredemo\fP program is provided as a simple coding
example.
.P
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
\fBpcredemo\fP:
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  ld.so.1: a.out: fatal: libpcre.so.0: open failed: No such file or directory
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This is caused by the way shared library support works on those systems. You
need to add
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  -R/usr/local/lib
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(for example) to the compile command to get round this problem.
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.SH AUTHOR
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Philip Hazel
University Computing Service
Cambridge CB2 3QH, England.
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.SH REVISION
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Last updated: 13 June 2007
Copyright (c) 1997-2007 University of Cambridge.
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