递推和递归

#include <stdio.h>
long fac(int n);
void main()
{int num;
printf("input the num:");
scanf("%d",&num);
printf("%d",fac(num));
getch();
}
long fac(int n)
{if(n==1) return 1;
else return n*fac(n-1);
}

#include <stdio.h>
long fac(int n);
void main()
{int num;
printf("input the num:");
scanf("%d",&num);
printf("%d",fac(num));
getch();
}
long fac(int n)
{long product=1,i;
for(i=1;i<n;i++)
product*=i;
return product;
}
自己好好想想吧！