noble (3) pcresample.3.gz

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.