Task

Write a function/procedure/subroutine that is called with an integer value and returns the middle three digits of the integer if possible or a clear indication of an error if this is not possible.

Note: The order of the middle digits should be preserved.

Your function should be tested with the following values; the first line should return valid answers, those of the second line should return clear indications of an error:

123, 12345, 1234567, 987654321, 10001, -10001, -123, -100, 100, -12345
1, 2, -1, -10, 2002, -2002, 0

Show your output on this page.




 
(defn middle3 [v]
  (let [no (Math/abs v)
        digits (str no)
        len (count digits)]
    (cond
      (< len 3) :too_short
      (even? len) :no_middle_in_even_no_of_digits
      :else (let [mid (/ len 2)
                  start (- mid 2)]
              (apply str
                     (take 3
                           (nthnext digits start)))))))
 
(def passes '(123 12345 1234567 987654321 10001 -10001 -123 -100 100 -12345))
(def fails '(1 2 -1 -10 2002 -2002 0))
 
 