What are the short comings of the Napier bones?

The elements of an integer-valued array can be set to 0 (i.e., the array can be cleared) recursively as follows: an array of size 0 is already cleared; otherwise, set the first element of the array to 0, and clear the rest of the array write a void function named clear that accepts an integer array, and the number of elements in the array and sets the elements of the array to 0.