Question

已要求我编写一个程序来验证字符串是否采用以下格式：

"<number><number><number><number><-><number><number><number><space><capitalized word/sentence>"

在满足要求时返回#t，在不满足要求时返回#f。

我尝试使用以下代码

(define (verify codpos)
      (cond ((string<=? (substring codpos 0 4) "9999")
             (string=? (substring codpos 4 5) "-")
             (string<=? (substring codpos 5 8) "999")
             (string=? (substring codpos 8 9) " ")
             (string>? (substring codpos 9 (string-length codpos)) "9")
             (string<? (substring codpos 9 (string-length codpos)) "a") #t)
            (else #f)))

无论是否满足条件，它都表示#t。我将不胜感激。我最近才刚开始编程，所以我不能像这样简单地练习。

Answer 1

您可以使用正则表达式来实现此目的：

#lang racket

(define (verify-rexpr s)
  (regexp-match? #px"^\\d{4}-\\d{3} (\\p{Lu}|\\s)*$" s))


(module+ test
  (require rackunit)
  ; -- 
  (check-true (verify-rexpr "1234-321 "))
  (check-false (verify-rexpr "1234-0s1 "))
  (check-true (verify-rexpr "9999-999 WORD"))
  (check-false (verify-rexpr "1234-321 word"))
  (check-true (verify-rexpr "1234-321 ALL CAPS SENTENCE"))
  (check-false (verify-rexpr "1234-321 Not ALL CAPS SENTENCE")))

Answer 2

我不理解大写单词/句子的意思是“带句子的大写单词”或“大写单词或句子”或“第一个字符串大写的句子”或“第一个字符串大写且长度可以是一个”。 “带有符号的句子”或“不允许其他符号”。

如果您想要这个“ 1234-123，这与符号和数字123相同。”

#lang racket

(define (varify str)
  (and (>= (string-length str) 10)
       (number? (string->number (substring str 0 4)))
       (string=? (substring str 4 5) "-")
       (number? (string->number (substring str 5 8)))
       (string=? (substring str 8 9) " ")
       (not (string=? (string-upcase (substring str 9 10))
                      (string-downcase (substring str 9 10))))
       (string=? (string-upcase (substring str 9))
                 (substring str 9))))

(varify "1234-123 THIS IS SENSTANCE WITH SYMBOL - @AND NUMBER123.") ; #true
(varify "1234-123 T") ; #true
(varify "1234-123 ") ; #false
(varify "1234-123 !HIS IS ENSTANCE WITH SYMBOL - @AND NUMBER123.") ; #false
(varify "1234-123  HIS IS SENSTANCE WITH SYMBOL - @AND NUMBER123.") ; #false
(varify "1234-123 tHIS IS SENSTANCE WITH SYMBOL - @AND NUMBER123.") ; #false
(varify "1234-12a THIS IS SENSTANCE WITH SYMBOL - @AND NUMBER123.") ; #false

如何验证字符串格式正确？

2 个答案: