Question

Scheme number computer

a. Write a recursive procedure (digits n) that computes the number of digits in the integer n using a recursive process. For example, (digits 42) should return 2 and (digits 13579) should return 5. You may make use of the built in floor predicate for truncating decimals to whole numbers.

b. Rewrite your procedure from part (a) using an iterative process. Call the function (digits-iter n).

Answer 1

a.

Program screenshots:

; Define the function digits ; the function uses the inbuilt floor function. (define (digits n) ; the function returns the number (+ 1 (floor (/ (log n) (log 10)))) : Call the function display(digits 12345)|

Sample Output:

=> 5

Code to Copy:

; Define the function digits

; the function uses the inbuilt floor function.

(define (digits n)

; the function returns the number

(+ 1 (floor (/ (log n) (log 10))))

)

; Call the function

display(digits 12345)

b.

Note: There is no iteration method in scheme. the scheme entirely works on the recursion. the iterative method in scheme also works on recursion.

Program screenshots:

;Definition of the function. (define (digits-iter n) ; Check the condition. (if (< n 10) ; call the function (+ 1 (digits-iter (/ n 10))))) display(digits-iter 12345)

Sample Output:

=> 5

Code to Copy:

;Definition of the function.

(define (digits-iter n)

; Check the condition.

(if (< n 10)

1

; call the function

(+ 1 (digits-iter (/ n 10) ))))

display(digits-iter 12345)