Python

#recursion

def num_of_strs(arr) -> int:
   """Accepts an array of strings and returns the total number of characters in the array."""
    if len(arr) == 1:
        return len(arr[0])
    return num_of_strs(arr[1:]) + len(arr[0])

assert num_of_strs(['x']) == 1
assert num_of_strs(['xy']) == 2
assert num_of_strs(['xy','z']) == 3
assert num_of_strs(['xy','z', 'abc', 'xyz']) == 9
assert num_of_strs(['ab','cx','yz']) == 6, num_of_strs(['ab','cx','yz'])