如何计算两个负整数c++之间的和？

#include <iostream>

int calculateSum(int num1, int num2) {
    int sum = 0;
    if (num1 < num2) {
        for (int i = num1; i <= num2; i++) {
            sum += i;
        }
    } else {
        for (int i = num2; i <= num1; i++) {
            sum += i;
        }
    }
    return sum;
}

int main() {
    int num1, num2;
    std::cout << "请输入两个负整数：" << std::endl;
    std::cin >> num1 >> num2;
    int sum = calculateSum(num1, num2);
    std::cout << "两个负整数之间的和为：" << sum << std::endl;
    return 0;
}