Loops 用迭代For循环求C++； #包括 使用名称空间std； int main（） { unsigned int num；unsigned long long int fact=1； cout>num； 对于（inti=1；i

，因为当我们将“0”乘以任何值时，它返回零

因此：

#include <iostream>
using namespace std;

int main ()
{
    unsigned int num; unsigned long long int fact = 1;
    cout << "Number = "; cin >> num;
    
    for (int i = 1; i <= num; ++i)
    {
        fact *= i;
    }
    cout << "Factorial = " << fact;
    return 0;
}

#include <iostream>
using namespace std;

int main ()
{
    unsigned int num; unsigned long long int fact = 0;
    cout << "Number = "; cin >> num;
    
    for (int i = 1; i <= num; ++i)
    {
        fact *= i; // 0 * i (i 1, 2, 3, 4...)

    }
    cout << "Factorial = " << fact;
    return 0;
}

cmd>a.exe
Number = 4
Factorial = 0```