C++ Primer 习题1.9

/*习题1.9*/
#include <iostream>
int main()
{
    int sum = 0;
    for (int i = -100; i <= 100; ++i)
        sum += i;
    std::cout << "sum的值是: " << sum << std::endl;
    return 0;
}

/*输出结果为0*/