factorial.cpp

该程序用来计算任何一个自然数的阶乘

// factorial.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"

#include <iostream>
using namespace std;
int fac(int i_nt)
{
	//int fac_ji;
	while(i_nt<0)
	{
		cout<<"Error!Please enter an positive integer:";
	    cin>>i_nt;
		if(i_nt>=0)
		{
			cout<<i_nt;
			break;
		}
             else
			continue;
	}
	
	if(i_nt==0)
		return 1;
	else
	{
		
		return fac(i_nt-1)*i_nt;
		//cout<<ii_nt;
		
        //return fac_ji;
	}
			
		
       
}
int _tmain(int argc, _TCHAR* argv[])
{
	cout<<"Enter an integer:";
	cout<<"\n";
	int i_nt;
	cin>>i_nt;
		if(i_nt>=0)
		cout<<i_nt;
	int product=fac(i_nt);

	cout<<"!="<<product<<endl;	
	
	return 0;
}