Palindrome Number

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

class Solution {
public:
    bool isPalindrome(int x) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (x < 0) {
           return false;
        }
        int oldx = x;
        int newx = 0;
        while (x) {
            newx = newx * 10 + x % 10;   // error: newx *= 10 + x % 10;
            x /= 10;
        }
        return oldx == newx;
    }
};