C++while循环语句求: 1、s=1-2+3-4+5-…+n 2、s=1+2-3+4+5-6+7+…+n

以下是两种C++ while循环语句求解的例子：

1. 求解 s = 1-2+3-4+5-...+n

#include <iostream>
using namespace std;

int main() {
    int n;
    cout << "请输入n的值：";
    cin >> n;
    
    int i = 1;
    int s = 0;
    int sign = 1;
    
    while (i <= n) {
        s += i * sign;
        sign = -sign;
        i++;
    }
    
    cout << "s = " << s << endl;
    
    return 0;
}

2. 求解 s = 1+2-3+4+5-6+7+...+n

#include <iostream>
using namespace std;

int main() {
    int n;
    cout << "请输入n的值：";
    cin >> n;
    
    int i = 1;
    int s = 0;
    int sign = 1;
    
    while (i <= n) {
        s += i * sign;
        sign = -sign;
        i++;
        if (i % 2 == 0) {
            i++;
        }
    }
    
    cout << "s = " << s << endl;
    
    return 0;
}