c語言遞歸求n的階乘

1.用循環

#include<stdio.h>
int main()
{
	int i,n,sum=1;
	scanf("%d",&n);
	for(i=1;i<=n;i++) {
		sum*=i; 
	}
	printf("%d!=%d",n,sum);
	
	getch();
	return 0;
}

2.用遞歸

#include<stdio.h>

int factorial(int n){
	if(n==0)
		return 1;
	return factorial(n-1)*n;
}
int main()
{
	int n,sum=1;
	scanf("%d",&n);
	printf("%d!=%d",n,factorial(n));
	
	getch();
	return 0;
}