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Full Discussion: A bug in Perl regex
Top Forums Shell Programming and Scripting A bug in Perl regex Post 302497754 by cronc on Friday 18th of February 2011 02:07:15 AM
Old 02-18-2011
A bug in Perl regex

The regex
Code:
'ab' =~ /((\w+)(?{print defined $2 ? "\$2=$2\n" : "\$2 not defined\n"})){2}/;

outputs:
Code:
$2=ab
$2 not defined
$2=b

Why $2 not defined? I think, the regex here must print $2=a. Is it a bug?

Last edited by pludi; 02-18-2011 at 05:18 AM..
 

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RE_COMP(3)						     Linux Programmer's Manual							RE_COMP(3)

NAME
re_comp, re_exec - BSD regex functions SYNOPSIS
#define _REGEX_RE_COMP #include <sys/types.h> #include <regex.h> char *re_comp(char *regex); int re_exec(char *string); DESCRIPTION
re_comp() is used to compile the null-terminated regular expression pointed to by regex. The compiled pattern occupies a static area, the pattern buffer, which is overwritten by subsequent use of re_comp(). If regex is NULL, no operation is performed and the pattern buffer's contents are not altered. re_exec() is used to assess whether the null-terminated string pointed to by string matches the previously compiled regex. RETURN VALUE
re_comp() returns NULL on successful compilation of regex otherwise it returns a pointer to an appropriate error message. re_exec() returns 1 for a successful match, zero for failure. CONFORMING TO
4.3BSD. NOTES
These functions are obsolete; the functions documented in regcomp(3) should be used instead. SEE ALSO
regcomp(3), regex(7), GNU regex manual COLOPHON
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. GNU
1995-07-14 RE_COMP(3)
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