PCRE2SAMPLE(3)PCRE2SAMPLE(3)NAME
PCRE2 - Perl-compatible regular expressions (revised API)
PCRE2 SAMPLE PROGRAM
A simple, complete demonstration program to get you started with using
PCRE2 is supplied in the file pcre2demo.c in the src directory in the
PCRE2 distribution. A listing of this program is given in the pcre2demo
documentation. If you do not have a copy of the PCRE2 distribution, you
can save this listing to re-create the contents of pcre2demo.c.
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.
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 possi‐
bility of matching an empty string. Comments in the code explain what
is going on.
If PCRE2 is installed in the standard include and library directories
for your operating system, you should be able to compile the demonstra‐
tion program using this command:
gcc -o pcre2demo pcre2demo.c -lpcre2-8
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 /usr/local, you can compile the demonstration program
using a command like this:
gcc -o pcre2demo -I/usr/local/include pcre2demo.c \
-L/usr/local/lib -lpcre2-8
Once you have compiled and linked the demonstration program, you can
run simple tests like this:
./pcre2demo 'cat|dog' 'the cat sat on the mat'
./pcre2demo -g 'cat|dog' 'the dog sat on the cat'
Note that there is a much more comprehensive test program, called
pcre2test, which supports many more facilities for testing regular
expressions using the PCRE2 libraries. The pcre2demo program is pro‐
vided as a simple coding example.
If you try to run pcre2demo when PCRE2 is not installed in the standard
library directory, you may get an error like this on some operating
systems (e.g. Solaris):
ld.so.1: a.out: fatal: libpcre2.so.0: open failed: No such file or
directory
This is caused by the way shared library support works on those sys‐
tems. You need to add
-R/usr/local/lib
(for example) to the compile command to get round this problem.
AUTHOR
Philip Hazel
University Computing Service
Cambridge, England.
REVISION
Last updated: 20 October 2014
Copyright (c) 1997-2014 University of Cambridge.
PCRE2 10.00 20 October 2014 PCRE2SAMPLE(3)
