1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
|
package bytes;
our $VERSION = '1.00';
$bytes::hint_bits = 0x00000008;
sub import {
$^H |= $bytes::hint_bits;
}
sub unimport {
$^H &= ~$bytes::hint_bits;
}
sub AUTOLOAD {
require "bytes_heavy.pl";
goto &$AUTOLOAD;
}
sub length ($);
1;
__END__
=head1 NAME
bytes - Perl pragma to force byte semantics rather than character semantics
=head1 SYNOPSIS
use bytes;
no bytes;
=head1 DESCRIPTION
WARNING: The implementation of Unicode support in Perl is incomplete.
See L<perlunicode> for the exact details.
The C<use bytes> pragma disables character semantics for the rest of the
lexical scope in which it appears. C<no bytes> can be used to reverse
the effect of C<use bytes> within the current lexical scope.
Perl normally assumes character semantics in the presence of character
data (i.e. data that has come from a source that has been marked as
being of a particular character encoding). When C<use bytes> is in
effect, the encoding is temporarily ignored, and each string is treated
as a series of bytes.
As an example, when Perl sees C<$x = chr(400)>, it encodes the character
in UTF8 and stores it in $x. Then it is marked as character data, so,
for instance, C<length $x> returns C<1>. However, in the scope of the
C<bytes> pragma, $x is treated as a series of bytes - the bytes that make
up the UTF8 encoding - and C<length $x> returns C<2>:
$x = chr(400);
print "Length is ", length $x, "\n"; # "Length is 1"
printf "Contents are %vd\n", $x; # "Contents are 400"
{
use bytes;
print "Length is ", length $x, "\n"; # "Length is 2"
printf "Contents are %vd\n", $x; # "Contents are 198.144"
}
For more on the implications and differences between character
semantics and byte semantics, see L<perlunicode>.
=head1 SEE ALSO
L<perlunicode>, L<utf8>
=cut
|
