Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-231, 231 - 1], then return 0.

Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-231, 231 - 1], then return 0.
Assume the environment does not allow you to store 64-bit integers (signed or unsigned).

This is a widely used question in programming competitions. Most instructors will give you this kind of questions in classrooms too. 

Here's a solution to reverse an integer in C++ without using 64-bit integers:

class Solution {

public:

    int reverse(int x) {

        int result = 0;

        while (x != 0) {

            int tail = x % 10;

            int newResult = result * 10 + tail;

            if ((newResult - tail) / 10 != result) {

                return 0;

            }

            result = newResult;

            x = x / 10;

        }

        return result;

    }

};

Explanation:

1. First, we initialize the result variable to 0.
2. In the while loop, we extract the last digit of x by taking the modulo 10 of x.
3. Then, we add this digit to the current result by multiplying the result by 10 and adding the extracted digit.
4. Before updating the result, we check if the reversed integer would go outside the signed 32-bit range. We do this by checking if (newResult - tail) / 10 is equal to the original result. If not, we return 0.
5. Finally, we divide x by 10 to remove the last digit and repeat the process until x becomes 0.