Leetcode Q9 Palindrome Number same code works in Java but not in C++

Question

I tried solving this problem: https://leetcode.com/problems/palindrome-number/ using code:

class Solution {
public:
    bool isPalindrome(int x) {
        int rev = 0;
        int temp = x;
        while(temp != 0 && temp > 0){
            rev = rev* 10;
            rev = rev + temp%10;
            temp = temp/10;
        }
        if (rev == x){
            return true;
        }
        else{
            return false;
        }
    }
};

and got this error in C++:

Line 7: Char 22: runtime error: signed integer overflow: 998765432 * 10 cannot be represented in type 'int' (solution.cpp)
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior prog_joined.cpp:16:22

The logically same code runs perfectly in Java though. Both java and c++ have int data type ranging from - 2^31 to 2^31-1 (Source: https://www.tutorialspoint.com/cplusplus/cpp_data_types.htm, https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html#:~:text=int%3A%20By%20default%2C%20the%20int,value%20of%20232%2D1.) So Why is this error showing up and how can I fix it? Thanks

Answer 1

You are getting this error because 9,987,654,320 is too big to fit in a 32-bit integer.

Solution: Use long long instead. That is:

long long rev = 0;
long long temp = x;

Also, I suggest clearly specify the type of parameter x.