处理计划口译员的困难

Question

我已将此代码写在纸上，据我所知它完全正确，但是一旦我在Dr. Dr.中运行它，我就会收到错误。我认为处理解释器有一些事情要做。这段代码有什么问题？

#lang scheme
(define (compare x y)
  (cond
    ((> x y) (display '(x is greater than y)))
    ((< x y) (display '(y is greater than x)))
    (else (display '(x and y are equal)))))

Answer 1

对于输出，我建议你使用printf：

(define (compare x y)
  (cond
    ((> x y) (printf "~a is greater than ~a\n" x y))
    ((< x y) (printf "~a is greater than ~a\n" y x))
    (else    (printf "~a and ~a are equal\n" x y))))

这样

(compare 2 3)
=> 3 is greater than 2

(compare 3 2)
=> 3 is greater than 2

(compare 3 3)
=> 3 and 3 are equal

另外，尝试使用DrRackets reindent all 功能，并避免在自己的行上关闭括号。