Question

我似乎在使用以下代码时遇到了一些问题：

   (define-struct speise (vegan name))

(define (vegan? speise1 speise2 speise3)
  (cond
    [(and (equal? speise1 true)
          (and (equal? speise2 true)
               (equal? speise3 true))) true]
    [else false]))

(check-expect (vegan? (make-speise true "Kuerbis-Marzipan-Suppe") (make-speise false "Mettkipferl") (make-speise true "Chilli-Spekulatius")) #false)
(check-expect (vegan? (make-speise false "Kuerbis-Fleisch-Suppe") (make-speise false "Mettkipferl") (make-speise false "Chilli-Fleisch-Spekulatius")) #false)
(check-expect (vegan? (make-speise true "Kuerbis-Marzipan-Suppe") (make-speise true "Salatkipferl") (make-speise true "Chilli-Spekulatius")) #true)

前两个测试没问题，但第三个测试导致异常，因为实际值与预期值不同。我只想检查所有3项 - 如果所有3项都是真的，那么我只想让程序打印为true。如果这3个中的一个是假的，那么它应该打印为false。很抱歉，这些变量都是德语。

Answer 1

那将是

(define-struct speise (vegan name))

(define (vegan? speise1 speise2 speise3)
  (and (speise-vegan speise1)
       (speise-vegan speise2)
       (speise-vegan speise3)))

(check-expect (vegan? (make-speise true "Kuerbis-Marzipan-Suppe") (make-speise false "Mettkipferl") (make-speise true "Chilli-Spekulatius")) #false)
(check-expect (vegan? (make-speise false "Kuerbis-Fleisch-Suppe") (make-speise false "Mettkipferl") (make-speise false "Chilli-Fleisch-Spekulatius")) #false)
(check-expect (vegan? (make-speise true "Kuerbis-Marzipan-Suppe") (make-speise true "Salatkipferl") (make-speise true "Chilli-Spekulatius")) #true)
(check-expect (vegan? (make-speise true "Something") (make-speise false "Somethingelse") (make-speise true "idontknow")) #false)

执行

Welcome to DrRacket, version 6.10.1 [3m].
Language: Beginning Student; memory limit: 128 MB.
All 4 tests passed!
>

我如何使用'平等？'在这种情况下适当吗？

1 个答案: