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

- NAME
- SYNOPSIS
- DESCRIPTION
- LIMITATIONS
- SEE ALSO

# NAME

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

# SYNOPSIS

        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;

# DESCRIPTION

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 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 similarly.

For more on the implications and differences between character semantics and byte semantics, see the perluniintro manpage and the perlunicode manpage.

# LIMITATIONS

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

# SEE ALSO

the perluniintro manpage, the perlunicode manpage, the utf8 manpage

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