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.
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.
On a Unix system that has PCRE installed in /usr/local, you can compile
the demonstration program using a command like this:
gcc -o pcredemo pcredemo.c -I/usr/local/include \
Then 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.
On some operating systems (e.g. Solaris) you may get an error like this
when you try to run pcredemo:
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
to the compile command to get round this problem.
Last updated: 28 January 2003Copyright (c) 1997-2003 University of Cambridge.