Answer:
#include <iostream> 
#include <cstdlib> 
 
int numOfDigits(int n) { 
 if (std::abs(n) <= 9) return 1; 
 return 1 + numOfDigits(n / 10); 
} 
 
int main() 
{ 
 int a[] = { 0, 1, -24, 3456, 12345 }; 
 for (int n : a) 
 std::cout << n << " has " << numOfDigits(n) << " digits" << std::endl; 
}
Step-by-step explanation:
This is the answer to your second question.
The first question requires some clarification on how the linked list is defined.