Clarify documentation on 'use bytes'.

Subject: Re: What does 'use bytes' "mean" ?
Message-ID: <20000918182425.A26765@deep-dark-truthful-mirror.perlhacker.org>

p4raw-id: //depot/perl@7354

1 files changed, 22 insertions, 5 deletions

diff --git a/lib/bytes.pm b/lib/bytes.pm
index f93d6158d9..f2f7e0157c 100644
--- a/lib/bytes.pm
+++ b/lib/bytes.pm
@@ -38,11 +38,28 @@ 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).
-
-To understand the implications and differences between character
+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