9 Palindrome Number

Determine whether an integer is a palindrome. Do this without extra space.

unsigned short num_digits(int num)
{
    long long int div = 1;
    int count = 0;
    while (div <= num) {
        count++;
        div *= 10;
    }
    return count;
}

unsigned short digitat(int num, int at, int num_digits)
{
    return int(num / pow(10, num_digits - at - 1)) % 10;
}

bool isPalindrome(int x) 
{
    if (x < 0) return false;
    const int numdig = num_digits(x);
    int start = 0;
    int end = numdig - 1;

    while (start < end) {
        int ok = digitat(x, start, numdig);
        int ok2 = digitat(x, end, numdig);
        if (digitat(x, start, numdig) != digitat(x, end, numdig))
            return false;
        start++; end--;
    }
    return true;
}