递归求阶乘
#includeint fac(int n){int f;if(n<0 || n>12)printf("data error!");else if(n==0||n==1)f=1;else f=fac(n-1)*n;return(f);}int main(){int n;int y;printf("来一个正整数:");scanf("%d",&n);y=fac(n);printf("%d!=%d\n",n,y);return 0;}