diff options
Diffstat (limited to 'pod/perlfaq6.pod')
| -rw-r--r-- | pod/perlfaq6.pod | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/pod/perlfaq6.pod b/pod/perlfaq6.pod index 168233bd1b..d19ba36bf8 100644 --- a/pod/perlfaq6.pod +++ b/pod/perlfaq6.pod @@ -1,6 +1,6 @@ =head1 NAME -perlfaq6 - Regular Expressions ($Revision: 1.20 $, $Date: 2003/01/03 20:05:28 $) +perlfaq6 - Regular Expressions ($Revision: 1.26 $, $Date: 2004/10/25 18:47:04 $) =head1 DESCRIPTION @@ -354,7 +354,7 @@ created by Jeffrey Friedl and later modified by Fred Curtis. $/ = undef; $_ = <>; - s#/\*[^*]*\*+([^/*][^*]*\*+)*/|("(\\.|[^"\\])*"|'(\\.|[^'\\])*'|.[^/"'\\]*)#$2#gs + s#/\*[^*]*\*+([^/*][^*]*\*+)*/|("(\\.|[^"\\])*"|'(\\.|[^'\\])*'|.[^/"'\\]*)#defined $2 ? $2 : ""#gse; print; This could, of course, be more legibly written with the C</x> modifier, adding @@ -395,11 +395,11 @@ whitespace and comments. Here it is expanded, courtesy of Fred Curtis. . ## Anything other char [^/"'\\]* ## Chars which doesn't start a comment, string or escape ) - }{$2}gxs; + }{defined $2 ? $2 : ""}gxse; A slight modification also removes C++ comments: - s#/\*[^*]*\*+([^/*][^*]*\*+)*/|//[^\n]*|("(\\.|[^"\\])*"|'(\\.|[^'\\])*'|.[^/"'\\]*)#$2#gs; + s#/\*[^*]*\*+([^/*][^*]*\*+)*/|//[^\n]*|("(\\.|[^"\\])*"|'(\\.|[^'\\])*'|.[^/"'\\]*)#defined $2 ? $2 : ""#gse; =head2 Can I use Perl regular expressions to match balanced text? @@ -745,17 +745,17 @@ Or like this: } Here's another, slightly less painful, way to do it from Benjamin -Goldberg: +Goldberg, who uses a zero-width negative look-behind assertion. - $martian =~ m/ - (?!<[A-Z]) - (?:[A-Z][A-Z])*? - GX - /x; + print "found GX!\n" if $martian =~ m/ + (?<![A-Z]) + (?:[A-Z][A-Z])*? + GX + /x; This succeeds if the "martian" character GX is in the string, and fails -otherwise. If you don't like using (?!<), you can replace (?!<[A-Z]) -with (?:^|[^A-Z]). +otherwise. If you don't like using (?<!), a zero-width negative +look-behind assertion, you can replace (?<![A-Z]) with (?:^|[^A-Z]). It does have the drawback of putting the wrong thing in $-[0] and $+[0], but this usually can be worked around. |