=head1 NAME
-perlfaq6 - Regexes ($Revision: 1.5 $, $Date: 2001/12/02 01:55:12 $)
+perlfaq6 - Regular Expressions ($Revision: 1.10 $, $Date: 2002/04/07 18:32:57 $)
=head1 DESCRIPTION
decoding a URL and checking whether something is a number are handled
with regular expressions, but those answers are found elsewhere in
this document (in L<perlfaq9>: ``How do I decode or create those %-encodings
-on the web'' and L<perfaq4>: ``How do I determine whether a scalar is
+on the web'' and L<perlfaq4>: ``How do I determine whether a scalar is
a number/whole/integer/float'', to be precise).
=head2 How can I hope to use regular expressions without creating illegible and unmaintainable code?
sub preserve_case {
my ($from, $to) = @_;
my ($lf, $lt) = map length, @_;
-
+
if ($lt < $lf) { $from = substr $from, 0, $lt }
else { $from .= substr $to, $lf }
-
+
return uc $to | ($from ^ uc $from);
}
=head2 What's wrong with using grep or map in a void context?
-Both grep and map build a return list, regardless of their context.
-This means you're making Perl go to the trouble of building up a
-return list that you then just ignore. That's no way to treat a
-programming language, you insensitive scoundrel!
+The problem is that both grep and map build a return list,
+regardless of the context. This means you're making Perl go
+to the trouble of building a list that you then just throw away.
+If the list is large, you waste both time and space. If your
+intent is to iterate over the list then use a for loop for this
+purpose.
=head2 How can I match strings with multibyte characters?
Starting from Perl 5.6 Perl has had some level of multibyte character
support. Perl 5.8 or later is recommended. Supported multibyte
-character repetoires include Unicode, and legacy encodings
+character repertoires include Unicode, and legacy encodings
through the Encode module. See L<perluniintro>, L<perlunicode>,
and L<Encode>.
=head1 AUTHOR AND COPYRIGHT
-Copyright (c) 1997-1999 Tom Christiansen and Nathan Torkington.
+Copyright (c) 1997-2002 Tom Christiansen and Nathan Torkington.
All rights reserved.
This documentation is free; you can redistribute it and/or modify it