=over

=item length EXPR

=item length

Returns the length in I<characters> of the value of EXPR.  If EXPR is
omitted, returns length of C<$_>.  Note that this cannot be used on
an entire array or hash to find out how many elements these have.
For that, use C<scalar @array> and C<scalar keys %hash> respectively.

Note the I<characters>: if the EXPR is in Unicode, you will get the
number of characters, not the number of bytes.  To get the length
in bytes, use C<do { use bytes; length(EXPR) }>, see L<bytes>.

=back