Horner's Rule C/C++ Using Recursion

Question

I learned about Horner's Rule here for the first time: Horner's rule in C++ Since I am learning about recursion ATM, I was wondering if it is possible to implement this algorithm using recursion ?

int HornerR( int a[], int n, int x, int index )
{
    if (index==n) return a[n];
    else  
        return x*HornerR(a,n ,x,index+1) + a[index];
} 

I think it's only possible with a fourth parameter.

Answer 1

You can do it with pointer arithmetic:

1. Base Case at the end of array (check n) return constant parameter
2. Recursive Case return current cell added to variable multiplied recursive call
3. Recursive Call move the array to next cell and update the counter (n)

Basically this lets you calculate the index variable by moving the array to the next position and sending that (and always using the first cell) instead of sending the whole array every time