Problem in digitizing a number and putting it in an array reversed

I am writing a C++ function which takes a positive number and returns an array containing its digits reversed.

#include <cmath>
#include <vector>

std::vector<int> digitize(unsigned long n) {
  int x = 1;
  for (int i = 1; n >= pow(10,i-1); ++i) { // Supposed to return the correct number of digits
    x = i;
  }
  std::vector<int> result;
  for (x; x > 0; --x) { // Takes the number of digits and begin assembling the array in reverse
    result[x] = n / pow(10,x-1);
  }
  return result;
}

During compiling, it returned warnings, and I'm pretty sure the function hasn't even done what I intended it to do yet. One of the warnings had something to do with the for (x; x > 0; --x) loop (some expression is unused). Shouldn't variable x carry over its value from the previous loop?

I tried modifying the second loop to use i instead of x, but as expected, the value and initialization of variable i didn't carry over from the first loop.

Solution

I would just rewrite the code to do a simpler approach.

Check for the special case of n being 0.
Write a loop that gets modulo 10 of n and store that value in the vector using push_back.
Divide n by 10
Repeat steps 2) and 3) until n is 0

Example:

#include <vector>
#include <iostream>

std::vector<int> digitize(unsigned long n) 
{
    std::vector<int> answer;
    if ( n == 0 )
        return {0};
    while (n > 0)
    {
        answer.push_back(n % 10);
        n /= 10;
    }
    return answer;
}

int main()
{
    auto v = digitize(1232196);
    for (auto val : v)
        std::cout << val;
}

Output: