求C++大神指教一下，给点意见或一些编程步骤

第一个还有点看得懂，但后面的就不太懂了

1. a)

    unsigned int x;
    unsigned int jc = 1;
    cout << "请输入一个非负整数：" << endl;
    cin >> x;
    while (x)
    {
        jc *= x;
        x--;
    }
    cout << "x!=" << jc << endl;

1. b)

    int n = 1;
    int jc = 1;
    float e = 0.0;
    int i = 0;
    cout << "请输入求和项数：" << endl;
    cin >> n;
    while (i < n)
    {
        if (i == 0)
            jc = 1;
        else
            jc *= i;
        i++;
        e += 1.0 / jc;
    }
    cout << "数学常量e=" << e << endl;

第三个类似的，不多说

a)
unsigned int x;
unsigned int jc = 1;
cout << "请输入一个非负整数：" << endl;
cin >> x;
while (x)
{
jc *= x;
x--;
}
cout << "x!=" << jc << endl;
b)
int n = 1;
int jc = 1;
float e = 0.0;
int i = 0;
cout << "请输入求和项数：" << endl;
cin >> n;
while (i < n)
{
if (i == 0)
jc = 1;
else
jc *= i;
i++;
e += 1.0 / jc;
}
cout << "数学常量e=" << e << endl;
第三个类似的，不多说