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.




(de middle3digits (N)
   (let (Lst (chop (abs N))  Len (length Lst))
      (tab (10 -2 -30)
         N
         ":"
         (cond
            ((> 3 Len) "not enough digits")
            ((bit? 1 Len)
               (head 3 (nth Lst (/ Len 2))) )
            (T "even number of digits") ) ) ) )