MirOS Manual: bytes(3p)

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


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


         use bytes;
         ... chr(...);       # or bytes::chr
         ... index(...);     # or bytes::index
         ... length(...);    # or bytes::length
         ... ord(...);       # or bytes::ord
         ... rindex(...);    # or bytes::rindex
         ... substr(...);    # or bytes::substr
         no bytes;


     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 encod-
     ing). When "use bytes" is in effect, the encoding is tem-
     porarily ignored, and each string is treated as a series of

     As an example, when Perl sees "$x = chr(400)", it encodes
     the character in UTF-8 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; # or "require bytes; bytes::length()"
             print "Length is ", length $x, "\n"; # "Length is 2"
             printf "Contents are %vd\n", $x;     # "Contents are 198.144"

     chr(), ord(), substr(), index() and rindex() behave simi-

     For more on the implications and differences between charac-
     ter semantics and byte semantics, see perluniintro and per-


     bytes::substr() does not work as an lvalue().

perl v5.8.8                2005-02-05                           1

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


     perluniintro, perlunicode, utf8

perl v5.8.8                2005-02-05                           2

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