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Revision 572 - (show annotations)
Wed Nov 17 17:55:57 2010 UTC (10 years, 11 months ago) by ph10
File size: 3124 byte(s)
Documentation updates and tidies.
3 PCRE - Perl-compatible regular expressions
5 .rs
6 .sp
7 A simple, complete demonstration program, to get you started with using PCRE,
8 is supplied in the file \fIpcredemo.c\fP in the PCRE distribution. A listing of
9 this program is given in the
10 .\" HREF
11 \fBpcredemo\fP
12 .\"
13 documentation. If you do not have a copy of the PCRE distribution, you can save
14 this listing to re-create \fIpcredemo.c\fP.
15 .P
16 The program compiles the regular expression that is its first argument, and
17 matches it against the subject string in its second argument. No PCRE options
18 are set, and default character tables are used. If matching succeeds, the
19 program outputs the portion of the subject that matched, together with the
20 contents of any captured substrings.
21 .P
22 If the -g option is given on the command line, the program then goes on to
23 check for further matches of the same regular expression in the same subject
24 string. The logic is a little bit tricky because of the possibility of matching
25 an empty string. Comments in the code explain what is going on.
26 .P
27 If PCRE is installed in the standard include and library directories for your
28 operating system, you should be able to compile the demonstration program using
29 this command:
30 .sp
31 gcc -o pcredemo pcredemo.c -lpcre
32 .sp
33 If PCRE is installed elsewhere, you may need to add additional options to the
34 command line. For example, on a Unix-like system that has PCRE installed in
35 \fI/usr/local\fP, you can compile the demonstration program using a command
36 like this:
37 .sp
38 .\" JOINSH
39 gcc -o pcredemo -I/usr/local/include pcredemo.c \e
40 -L/usr/local/lib -lpcre
41 .sp
42 In a Windows environment, if you want to statically link the program against a
43 non-dll \fBpcre.a\fP file, you must uncomment the line that defines PCRE_STATIC
44 before including \fBpcre.h\fP, because otherwise the \fBpcre_malloc()\fP and
45 \fBpcre_free()\fP exported functions will be declared
46 \fB__declspec(dllimport)\fP, with unwanted results.
47 .P
48 Once you have compiled and linked the demonstration program, you can run simple
49 tests like this:
50 .sp
51 ./pcredemo 'cat|dog' 'the cat sat on the mat'
52 ./pcredemo -g 'cat|dog' 'the dog sat on the cat'
53 .sp
54 Note that there is a much more comprehensive test program, called
55 .\" HREF
56 \fBpcretest\fP,
57 .\"
58 which supports many more facilities for testing regular expressions and the
59 PCRE library. The
60 .\" HREF
61 \fBpcredemo\fP
62 .\"
63 program is provided as a simple coding example.
64 .P
65 If you try to run
66 .\" HREF
67 \fBpcredemo\fP
68 .\"
69 when PCRE is not installed in the standard library directory, you may get an
70 error like this on some operating systems (e.g. Solaris):
71 .sp
72 ld.so.1: a.out: fatal: libpcre.so.0: open failed: No such file or directory
73 .sp
74 This is caused by the way shared library support works on those systems. You
75 need to add
76 .sp
77 -R/usr/local/lib
78 .sp
79 (for example) to the compile command to get round this problem.
80 .
81 .
83 .rs
84 .sp
85 .nf
86 Philip Hazel
87 University Computing Service
88 Cambridge CB2 3QH, England.
89 .fi
90 .
91 .
93 .rs
94 .sp
95 .nf
96 Last updated: 17 November 2010
97 Copyright (c) 1997-2010 University of Cambridge.
98 .fi


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