编辑代码

#include <stdio.h>
int main()
{
	long fac(int n);
	int n;
	long fact=0;
	printf("please input a interger number:\n");
	scanf("%d",&n);
	fact=fac(n);
	printf("%d!=%ld\n",n,fact);
	return 0;
}

long fac(int n)
{
	int i;
	long fac=1;
	for(i=1;i<=n;i++)
	fac=fac*i;
return fac;	
}