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.