leetcode Reverse Integer

class Solution {public:    int reverse(int x) {        const int maxlen = 100;        char str[maxlen];        memset(str, 0, sizeof(str));        if(x == 0x80000000){            return 0;        }        int storex = x;        if(x < 0){            x = x * (-1);        }        sprintf(str, "%d", x);        char rstr[maxlen];        memset(rstr, 0, sizeof(rstr));        int len = strlen(str);        int idx = 0;        for(int i = len - 1; i >= 0; --i){            rstr[idx++] = str[i];        }        rstr[idx] = '\0';        long long res = 0;        for(int i = 0; i < idx; ++i){            res = res * 10 + (rstr[i] - '0');        }        if(res >= 0x7fffffff){            return 0; //overflow        }        if(storex < 0){            res *= (-1);        }        return res;    }};