Please test all your programs carefully and include all the test cases
with your program. You should have at least 3 tests for each function, except the ones that produce an image or a scene.
Every function must have a contract.
Recall the function first-letter-A? that
we wrote in
class. Here is our code:
;; (first-letter-A? str) -> boolean
;; str: string
;; consumes a string, returns true
;; if this string starts with a capital A, otherwise returns false
(define (first-letter-A? str)
(string=? (string-ith str 0) "A"))
(check-expect (first-letter-A? "AbC") #true)
(check-expect (first-letter-A? "abC") #false)
(check-expect (first-letter-A? "bcde") #false)
;(check-expect (first-letter-A? "") #false)
(check-expect (first-letter-A? "aaAAaaaa") #false)
#false for it, as the commented out test case
indicates). You can use cond or if or
(better!) combine your conditions using boolean operations, such
as and, or, not (either approach will get full credit if
works correctly). first-letter-a-or-A? that returns #true if this string starts with "A" or "a"
and false otherwise. It must return false for an empty string. Make sure to write test cases and the description (contract) for your function.
Exercises 37 (3 points), 38 (4 points, assume that the image is a square of image-height by image-width), 39 (3 points), and 40 (3 points) in Section 3.2.