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 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
       possibility of matching an empty string. Comments in the code explain what is going on.

       The  code  in  pcre2demo.c  is an 8-bit program that uses the PCRE2 8-bit library. It handles strings and
       characters that are stored in 8-bit code units.  By default, one character corresponds to one code  unit,
       but  if  the  pattern  starts  with "(*UTF)", both it and the subject are treated as UTF-8 strings, where
       characters may occupy multiple code units.

       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 a command like this:

         cc -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:

         cc -o pcre2demo -I/usr/local/include pcre2demo.c \
            -L/usr/local/lib -lpcre2-8

       Once you have built 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 all three PCRE2 libraries (8-bit,  16-bit,  and  32-bit,
       though  not all three need be installed). The pcre2demo program is provided as a relatively 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: pcre2demo: fatal: libpcre2-8.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, England.

REVISION

       Last updated: 02 February 2016
       Copyright (c) 1997-2016 University of Cambridge.