Arrays in C++

So lets say I have an array, int array[3] = {123, 456, 789}.
If I wanted to take the first number of each value of the array and store it in another array, say int first[3];, how would I do that? I tried using a pointer to read the first memory address of each value of the array but it keeps returning the full array.


(define (first lis)
  (map (compose (curry (flip -) (char->integer #\0))
                char->integer
                (curry (flip string-ref) 0)
                number->string
                abs)
       lis))