static int myAtoi(string str) {
        bool minus = false;
        int i = 0;
        while (str[i] == ‘ ‘)i++;
        if (str[i] == ‘+‘ || str[i] == ‘-‘) {
            if (str[i] == ‘-‘)
                minus = true;
            i++;
        }
        int result = 0;
        for (; i < str.length(); i++) {
            int digit = str[i] - ‘0‘;
            if (str[i] < ‘0‘ || str[i] > ‘9‘)
                break;
            if (minus && result > -((INT_MIN + digit) / 10))
                return INT_MIN;
            else if (!minus && result > ((INT_MAX - digit) / 10))
                return INT_MAX;
            result = result * 10 + digit;
        }
        return minus ? -result : result;
    }