#include<iostream>
using namespace std;
const int size = 6; //輸入階乘數
int main()
{   
    long long factorial[size];
    factorial[1] = factorial[0] = 1LL;
    for (int i = 2; i < size; i++)
    {
        factorial[i] = i * factorial[i - 1];
    }
    for (int i = 0; i < size; i++)
        cout 
 
<< i << "! = " << factorial[i] << endl;
    cin.get();
    return 0;
}

輸出：

0! = 1
1! = 1
2! = 2
3! = 6
4! = 24
5! = 120