阶乘算法

// factorial.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

#include <CSTDIO>
#include <CSTDLIB>
#include <IOSTREAM>

using namespace std;

// 1、循环
long fact(int n)
{
	int i;
	long result = 1;

	for (i = 1; i <= n; i++)
	{
		result *= i;
	}
	return result;
}

// 2、递归
// n! = n * (n - 1)!
long fact1(int n)
{
	if (n <= 1)
	{
		return 1;
	}
	else
	{
		return n * fact1(n-1);
	}
}

int main(int argc, char* argv[])
{

	int i;
	cout<<"enter factorial number: "<<endl;
	cin>>i;

	cout<<i<<" factorial: "<<fact(i)<<endl;
	cout<<i<<" factorial recursion:  "<<fact1(i)<<endl;

	return 0;
}