PCRESAMPLE(3) Introduction to Library Functions PCRESAMPLE(3)

NAME

PCRE - Perl-compatible regular expressions

PCRE SAMPLE PROGRAM

A simple, complete demonstration program, to get you started with
using PCRE, is supplied in the file pcredemo.c in the PCRE
distribution. A listing of this program is given in the pcredemo
documentation. If you do not have a copy of the PCRE distribution,
you can save this listing to re-create pcredemo.c.

The demonstration program, which uses the original PCRE 8-bit
library, 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.

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.

If PCRE 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:

gcc -o pcredemo pcredemo.c -lpcre

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 /usr/local, you can compile the demonstration
program using a command like this:

gcc -o pcredemo -I/usr/local/include pcredemo.c \
-L/usr/local/lib -lpcre

In a Windows environment, if you want to statically link the program
against a non-dll pcre.a file, you must uncomment the line that
defines PCRE_STATIC before including pcre.h, because otherwise the
pcre_malloc() and pcre_free() exported functions will be declared
__declspec(dllimport), with unwanted results.

Once you have compiled and linked the demonstration program, you can
run simple tests like this:

./pcredemo 'cat|dog' 'the cat sat on the mat'
./pcredemo -g 'cat|dog' 'the dog sat on the cat'

Note that there is a much more comprehensive test program, called
pcretest, which supports many more facilities for testing regular
expressions and both PCRE libraries. The pcredemo program is provided
as a simple coding example.

If you try to run pcredemo when PCRE 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: libpcre.so.0: open failed: No such file or
directory

This is caused by the way shared library support works on those
systems. 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 CB2 3QH, England.

REVISION

Last updated: 10 January 2012
Copyright (c) 1997-2012 University of Cambridge.

PCRE 8.30 10 January 2012 PCRESAMPLE(3)