c++分别使用while、for、do+while语句计算s=1!+3!+5!+7！+n!

以下是使用while、for、do+while语句计算s=1!+3!+5!+7！+n!的C++代码实现：

1. while语句实现：

#include <iostream>
using namespace std;

int main() {
    int n = 7;
    int i = 1;
    int s = 0;
    int fac = 1;
    while (i <= n) {
        fac = 1;
        int j = 1;
        while (j <= i) {
            fac *= j;
            j++;
        }
        s += fac;
        i += 2;
    }
    cout << "s = " << s << endl;
    return 0;
}

2. for语句实现：

#include <iostream>
using namespace std;

int main() {
    int n = 7;
    int s = 0;
    for (int i = 1; i <= n; i += 2) {
        int fac = 1;
        for (int j = 1; j <= i; j++) {
            fac *= j;
        }
        s += fac;
    }
    cout << "s = " << s << endl;
    return 0;
}

3. do+while语句实现：

#include <iostream>
using namespace std;

int main() {
    int n = 7;
    int i = 1;
    int s = 0;
    do {
        int fac = 1;
        int j = 1;
        do {
            fac *= j;
            j++;
        } while (j <= i);
        s += fac;
        i += 2;
    } while (i <= n);
    cout << "s = " << s << endl;
    return 0;
}