魔术八球？在方案中
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就像Magic-8球游戏一样，我正在尝试构建一个模型，该模型可以按以下顺序回答不同的问题：
\“可以肯定的是\”
\“前景良好\”
\“稍后再询问\\”
\\“前景不太好\\”。
如果问题为空，则产生“您没有提出问题，请重试”，表示为（无答案）
我为这个问题写下了代码，但是空的情况不起作用。
也就是说，“ 0”应产生“您没有问问题，请重试”。
;; 8-ball-answers: (listof string)
(define 8-ball-answers (list \"It is certain\" \"Outlook good\" \"Ask again later\" \"Outlook not so good\"))
;; no-answer: string
;; Purpose: correct form of string to produce when magic-8-ball consumes empty string
(define no-answer \"you did not ask a question, try again\")
;;magic-8-ball: string -> string
;;Purpose: consumes a string and produces a string
;;Effects: modifies (8-ball-answers). If the string is empty, produces
;; \"you did not ask a question, try again\". Otherwise, changes
;; \"It is certain\" to \"Outlook good\",
;; \"Outlook is good\" to \"Ask again later\",
;; \"Ask again later\" to \"Outlook not so good\",
;; and \"Outlook not so good\" to \"It is certain\".
(define (magic-8-ball s)
(local
[
;; new-list represents the new value of the list 8-ball-answers
;; after every time the function is called.
(define next-answer (first 8-ball-answers))]
(begin
(cond [(equal? s \"\") no-answer]
[else (set! 8-ball-answers (append (rest 8-ball-answers)
(list next-answer)))])
next-answer)))
(check-expect (and (equal? (magic-8-ball \"Do you love me?\")
\"It is certain\")
(equal? (magic-8-ball \"How is your life?\")
\"Outlook good\")
(equal? (magic-8-ball \"\")
\"you did not ask a question, try again\")
(equal? (magic-8-ball \"2nd0A-wmQ232.asdA?\")
\"Ask again later\")
(equal? (magic-8-ball \"No questions here\")
\"Outlook not so good\")
(equal? (magic-8-ball \"Now do you hate me?\")
\"It is certain\"))
true))
没有找到相关结果
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1 个回复
傻零凰死授
(begin (cond [(equal? s \"\") no-answer] [else (set! 8-ball-answers (append (rest 8-ball-answers) (list next-answer)))]) next-answer)，与条件结果无关。我想象您可能希望您的条件在循环答案后返回。问题是您的7英镑。您测试一个条件，然后返回。也许您想要这样的东西：(cond [(equal? s \"\") no-answer] [else (begin (set! 8-ball-answers (append (rest 8-ball-answers) (list next-answer))) next-answer)])