在球拍中比较变量？

Question

我正在尝试创建一个函数，要求用户输入多个整数，然后输出变量中最小的那个。（例如，输入1、4、67的结果为1。）

我尝试分别请求每个整数并将它们存储为变量，但是在建立一个if语句是否良好时会遇到问题，该语句将打印int1，int2或int3，具体取决于哪一个最小。

#lang typed/racket
(require typed/test-engine/racket-tests)
(require "../include/cs151-core.rkt")
;; The necessary .rkt files...


(printf "Enter your first integer: ")
;; Requests user input for first variable
(define int1 (read-line))
;; Stores user input in variable int1
(printf "Enter your second integer: ")
;; Requests user input for second variable
(define int2 (read-line))
;; Stores user input in int2 variable
(printf "Enter your third and final integer: ")
;; Requests user input for third variable
(define int3 (read-line))
;; Stores user input in third variable int3


; (define (int-sorter int1)
;   (cond
;     [(< int1 int2)
;      (display int1)]
;     [(> int1 int2)
;       (cond
;         [(< int2 int3)
;          (display int2)]
;         [(display int3)])]))

Answer 1

如果用户输入是列表，我们可以放弃更大的数字。

; lon = list-of-number
(define (mini lon)
  (local ((define (aux n lon)
            (cond
              [(empty? lon) n]
              [(< n (first lon))
               (aux n (rest lon))]
              [(> n (first lon))
               (aux (first lon) (rest lon))]
              [else
               (aux (first lon) (rest lon))])))
    (aux (first lon) lon)))

(mini(range -100 100)) ; -100


; or use foldr

(define (mini-v2 lon)
  (local ((define (which-smaller? n1 n2)
            (cond
              [(< n1 n2) n1]
              [(> n1 n2) n2]
              [(= n1 n2) n1])))
    (foldr which-smaller? 0 lon)))


(mini-v2 (range -100 100)) ; -100

如果输入许多变量，lambda将使参数成为列表。然后，我们按升序对其进行排序。然后第一个元素最小。

#lang racket

(define (mini . n)
  (first (sort n <)))

(mini (range -100 100)) ; -100