.TH PCRE2SAMPLE 3 "20 October 2014" "PCRE2 10.00"
.SH NAME
PCRE2 - Perl-compatible regular expressions (revised API)
.SH "PCRE2 SAMPLE PROGRAM"
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A simple, complete demonstration program to get you started with using PCRE2 is
supplied in the file \fIpcre2demo.c\fP in the \fBsrc\fP directory in the PCRE2
distribution. A listing of this program is given in the
.\" HREF
\fBpcre2demo\fP
.\"
documentation. If you do not have a copy of the PCRE2 distribution, you can
save this listing to re-create the contents of \fIpcre2demo.c\fP.
.P
The demonstration program, which uses the PCRE2 8-bit library, compiles the
regular expression that is its first argument, and matches it against the
subject string in its second argument. No PCRE2 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
If PCRE2 is installed in the standard include and library directories for your
operating system, you should be able to compile the demonstration program using
this command:
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  gcc -o pcre2demo pcre2demo.c -lpcre2-8
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If PCRE2 is installed elsewhere, you may need to add additional options to the
command line. For example, on a Unix-like system that has PCRE2 installed in
\fI/usr/local\fP, you can compile the demonstration program using a command
like this:
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.\" JOINSH
  gcc -o pcre2demo -I/usr/local/include pcre2demo.c \e
      -L/usr/local/lib -lpcre2-8
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.P
Once you have compiled and linked the demonstration program, you can run simple
tests like this:
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  ./pcre2demo 'cat|dog' 'the cat sat on the mat'
  ./pcre2demo -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
\fBpcre2test\fP,
.\"
which supports many more facilities for testing regular expressions using the
PCRE2 libraries. The
.\" HREF
\fBpcre2demo\fP
.\"
program is provided as a simple coding example.
.P
If you try to run
.\" HREF
\fBpcre2demo\fP
.\"
when PCRE2 is not installed in the standard library directory, you may get an
error like this on some operating systems (e.g. Solaris):
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  ld.so.1: a.out: fatal: libpcre2.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, England.
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.SH REVISION
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Last updated: 20 October 2014
Copyright (c) 1997-2014 University of Cambridge.
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