1PCRE2SAMPLE(3)             Library Functions Manual             PCRE2SAMPLE(3)
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NAME

6       PCRE2 - Perl-compatible regular expressions (revised API)
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PCRE2 SAMPLE PROGRAM

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10       A  simple, complete demonstration program to get you started with using
11       PCRE2 is supplied in the file pcre2demo.c in the src directory  in  the
12       PCRE2 distribution. A listing of this program is given in the pcre2demo
13       documentation. If you do not have a copy of the PCRE2 distribution, you
14       can save this listing to re-create the contents of pcre2demo.c.
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16       The  demonstration  program compiles the regular expression that is its
17       first argument, and matches it against the subject string in its second
18       argument.  No  PCRE2  options are set, and default character tables are
19       used. If matching succeeds, the program outputs the portion of the sub‐
20       ject  that  matched,  together  with  the contents of any captured sub‐
21       strings.
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23       If the -g option is given on the command line, the program then goes on
24       to check for further matches of the same regular expression in the same
25       subject string. The logic is a little bit tricky because of the  possi‐
26       bility  of  matching an empty string. Comments in the code explain what
27       is going on.
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29       The code in pcre2demo.c is an 8-bit program that uses the  PCRE2  8-bit
30       library.  It  handles  strings  and characters that are stored in 8-bit
31       code units.  By default, one character corresponds to  one  code  unit,
32       but  if  the  pattern starts with "(*UTF)", both it and the subject are
33       treated as UTF-8 strings, where characters  may  occupy  multiple  code
34       units.
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36       If  PCRE2  is installed in the standard include and library directories
37       for your operating system, you should be able to compile the demonstra‐
38       tion program using a command like this:
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40         cc -o pcre2demo pcre2demo.c -lpcre2-8
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42       If PCRE2 is installed elsewhere, you may need to add additional options
43       to the command line. For example, on a Unix-like system that has  PCRE2
44       installed  in  /usr/local,  you  can  compile the demonstration program
45       using a command like this:
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47         cc -o pcre2demo -I/usr/local/include pcre2demo.c \
48            -L/usr/local/lib -lpcre2-8
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50       Once you have built the demonstration program, you can run simple tests
51       like this:
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53         ./pcre2demo 'cat|dog' 'the cat sat on the mat'
54         ./pcre2demo -g 'cat|dog' 'the dog sat on the cat'
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56       Note  that  there  is  a  much  more comprehensive test program, called
57       pcre2test, which supports many  more  facilities  for  testing  regular
58       expressions using all three PCRE2 libraries (8-bit, 16-bit, and 32-bit,
59       though not all three need be installed). The pcre2demo program is  pro‐
60       vided as a relatively simple coding example.
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62       If you try to run pcre2demo when PCRE2 is not installed in the standard
63       library directory, you may get an error like  this  on  some  operating
64       systems (e.g. Solaris):
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66         ld.so.1: pcre2demo: fatal: libpcre2-8.so.0: open failed: No such file
67       or directory
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69       This is caused by the way shared library support works  on  those  sys‐
70       tems. You need to add
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72         -R/usr/local/lib
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74       (for example) to the compile command to get round this problem.
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AUTHOR

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78       Philip Hazel
79       University Computing Service
80       Cambridge, England.
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REVISION

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84       Last updated: 02 February 2016
85       Copyright (c) 1997-2016 University of Cambridge.
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89PCRE2 10.22                    02 February 2016                 PCRE2SAMPLE(3)