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 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 match‐
ing 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 PCRE 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 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 \
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_mal‐
loc() 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 the PCRE library. 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
This is caused by the way shared library support works on those sys‐
tems. You need to add
(for example) to the compile command to get round this problem.
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Last updated: 17 November 2010
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