Commit | Line | Data |
---|---|---|
657b208b | 1 | package bytes; |
5bc28da9 | 2 | |
65016084 | 3 | our $VERSION = '1.01'; |
b75c8c73 | 4 | |
d5448623 GS |
5 | $bytes::hint_bits = 0x00000008; |
6 | ||
5bc28da9 | 7 | sub import { |
d5448623 | 8 | $^H |= $bytes::hint_bits; |
5bc28da9 NIS |
9 | } |
10 | ||
11 | sub unimport { | |
d5448623 | 12 | $^H &= ~$bytes::hint_bits; |
5bc28da9 NIS |
13 | } |
14 | ||
15 | sub AUTOLOAD { | |
657b208b | 16 | require "bytes_heavy.pl"; |
5bc28da9 NIS |
17 | goto &$AUTOLOAD; |
18 | } | |
19 | ||
20 | sub length ($); | |
579f6b36 JH |
21 | sub chr ($); |
22 | sub ord ($); | |
23 | sub substr ($$;$$); | |
24 | sub index ($$;$); | |
25 | sub rindex ($$;$); | |
5bc28da9 NIS |
26 | |
27 | 1; | |
28 | __END__ | |
29 | ||
30 | =head1 NAME | |
31 | ||
657b208b | 32 | bytes - Perl pragma to force byte semantics rather than character semantics |
5bc28da9 NIS |
33 | |
34 | =head1 SYNOPSIS | |
35 | ||
657b208b | 36 | use bytes; |
579f6b36 JH |
37 | ... chr(...); # or bytes::chr |
38 | ... index(...); # or bytes::index | |
39 | ... length(...); # or bytes::length | |
40 | ... ord(...); # or bytes::ord | |
41 | ... rindex(...); # or bytes::rindex | |
42 | ... substr(...); # or bytes::substr | |
657b208b | 43 | no bytes; |
5bc28da9 | 44 | |
579f6b36 | 45 | |
5bc28da9 NIS |
46 | =head1 DESCRIPTION |
47 | ||
657b208b GS |
48 | The C<use bytes> pragma disables character semantics for the rest of the |
49 | lexical scope in which it appears. C<no bytes> can be used to reverse | |
50 | the effect of C<use bytes> within the current lexical scope. | |
393fec97 | 51 | |
5de28535 SC |
52 | Perl normally assumes character semantics in the presence of character |
53 | data (i.e. data that has come from a source that has been marked as | |
54 | being of a particular character encoding). When C<use bytes> is in | |
55 | effect, the encoding is temporarily ignored, and each string is treated | |
56 | as a series of bytes. | |
57 | ||
58 | As an example, when Perl sees C<$x = chr(400)>, it encodes the character | |
c26c758b | 59 | in UTF-8 and stores it in $x. Then it is marked as character data, so, |
5de28535 SC |
60 | for instance, C<length $x> returns C<1>. However, in the scope of the |
61 | C<bytes> pragma, $x is treated as a series of bytes - the bytes that make | |
62 | up the UTF8 encoding - and C<length $x> returns C<2>: | |
63 | ||
64 | $x = chr(400); | |
65 | print "Length is ", length $x, "\n"; # "Length is 1" | |
66 | printf "Contents are %vd\n", $x; # "Contents are 400" | |
67 | { | |
579f6b36 | 68 | use bytes; # or "require bytes; bytes::length()" |
5de28535 SC |
69 | print "Length is ", length $x, "\n"; # "Length is 2" |
70 | printf "Contents are %vd\n", $x; # "Contents are 198.144" | |
71 | } | |
72 | ||
579f6b36 JH |
73 | chr(), ord(), substr(), index() and rindex() behave similarly. |
74 | ||
5de28535 | 75 | For more on the implications and differences between character |
579f6b36 JH |
76 | semantics and byte semantics, see L<perluniintro> and L<perlunicode>. |
77 | ||
78 | =head1 LIMITATIONS | |
79 | ||
80 | bytes::substr() does not work as an lvalue(). | |
393fec97 GS |
81 | |
82 | =head1 SEE ALSO | |
83 | ||
579f6b36 | 84 | L<perluniintro>, L<perlunicode>, L<utf8> |
5bc28da9 NIS |
85 | |
86 | =cut |