Here are some good questions to ask before coding. Bonus points for you if you have already thought through this!

If the integer‘s last digit is 0, what should the output be? ie, cases such as 10, 100.

Did you notice that the reversed integer might overflow? Assume the input is a 32-bit integer, then the reverse of 1000000003 overflows. How should you handle such cases?

For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

Update (2014-11-10):
Test cases had been added to test the overflow behavior.

if(x < 0) // it means x = INT_MIN                return 0;

class Solution {    public:        int reverse(int x) {            // Start typing your C/C++ solution below            // DO NOT write int main() function            int sign = x > 0 ? 1 : -1;             x = abs(x);                        if(x < 0) // it means x = INT_MIN                return 0;                            int ret = 0;            while(x)            {                   if(ret > INT_MAX/10)                    return 0;                int digit = x % 10;                 ret = ret * 10 + digit;                x /= 10;             }               return ret * sign;        }   };