


bytes(3p)        Perl Programmers Reference Guide       bytes(3p)


NAME
       bytes - Perl pragma to force byte semantics rather than
       character semantics

SYNOPSIS
           use bytes;
           no bytes;


DESCRIPTION
       WARNING: The implementation of Unicode support in Perl is
       incomplete.  See the perlunicode manpage for the exact
       details.

       The "use bytes" pragma disables character semantics for
       the rest of the lexical scope in which it appears.  "no
       bytes" can be used to reverse the effect of "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 "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 "$x = chr(400)", it encodes
       the character in UTF8 and stores it in $x. Then it is
       marked as character data, so, for instance, "length $x"
       returns "1". However, in the scope of the "bytes" pragma,
       $x is treated as a series of bytes - the bytes that make
       up the UTF8 encoding - and "length $x" returns "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 char-
       acter semantics and byte semantics, see the perlunicode
       manpage.

SEE ALSO
       the perlunicode manpage, the utf8 manpage









2001-05-24                 perl v5.6.1                          1


