--- swapcase
--- swapcase!

    Ƥʸʸˡʸʸѹޤ

    swapcase ִʸ֤ޤ
    swapcase!  self ѹ֤ޤִ
    ʤä nil ֤ޤ

    $KCODE ŬڤꤵƤʤСɤΰѴ
    Ƥޤޤ(ϡShiftJIS ɤǵޤ)
    դˡ$KCODE ꤷƤޥХʸΥե٥å
    Ͻޤ

        # -*- Coding: shift_jis -*-
        $KCODE ='n'
        puts "".swapcase # => 

    upcase, downcase,
    capitalize ⻲ȤƤ

