=head1 NAME
-perlfaq6 - Regexes ($Revision: 1.4 $, $Date: 2001/11/09 08:06:04 $)
+perlfaq6 - Regular Expressions ($Revision: 1.12 $, $Date: 2002/06/01 22:31:09 $)
=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?
=head2 I'm having trouble matching over more than one line. What's wrong?
-Either you don't have more than one line in the string you're looking at
-(probably), or else you aren't using the correct modifier(s) on your
-pattern (possibly).
+Either you don't have more than one line in the string you're looking
+at (probably), or else you aren't using the correct modifier(s) on
+your pattern (possibly).
There are many ways to get multiline data into a string. If you want
it to happen automatically while reading input, you'll want to set $/
close FH;
## Get a read/write filehandle to it.
- $fh = new FileHandle "+<file";
+ $fh = new IO::File "+<file";
## Attach it to a "stream" object.
use Net::Telnet;
sub preserve_case {
my ($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?
-This is hard, and there's no good way. Perl does not directly support
-wide characters. It pretends that a byte and a character are
-synonymous. The following set of approaches was offered by Jeffrey
-Friedl, whose article in issue #5 of The Perl Journal talks about this
-very matter.
+Starting from Perl 5.6 Perl has had some level of multibyte character
+support. Perl 5.8 or later is recommended. Supported multibyte
+character repertoires include Unicode, and legacy encodings
+through the Encode module. See L<perluniintro>, L<perlunicode>,
+and L<Encode>.
+
+If you are stuck with older Perls, you can do Unicode with the
+C<Unicode::String> module, and character conversions using the
+C<Unicode::Map8> and C<Unicode::Map> modules. If you are using
+Japanese encodings, you might try using the jperl 5.005_03.
+
+Finally, the following set of approaches was offered by Jeffrey
+Friedl, whose article in issue #5 of The Perl Journal talks about
+this very matter.
Let's suppose you have some weird Martian encoding where pairs of
ASCII uppercase letters encode single Martian letters (i.e. the two
=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