--- printf(format[, arg[, ...]])

    C  printf Ʊ褦ˡformat ˽
    ʸѴơself ˽Ϥޤ

     IO ǤʤȡάǤʤȤ
     printf ƱǤ
    ΰξܺ٤ˤĤƤ sprintfեޥå 򻲾ȤƤ

    nil ֤ޤ

