One more answer which don't allocate fuge memory.
eval(join(map(range(1, line('$')),
'len(iconv(getline(v:val)."\n",&encoding,"char"))'),'+'))-- You received this message from the "vim_dev" maillist. Do not top-post! Type your reply below the text you are replying to. For more information, visit http://www.vim.org/maillist.php
