/* recursion.c */
/* 递归 */ #include <stdio.h> void interface(void);
/* 斐波那契数列以及阶乘函数声明 */
long long factorial(int n);
void fibonacci(int x, int y, int stop); int main(){
int flag, number; interface();
for(;;){
printf("Command: ");
scanf("%d", &flag);
switch(flag){
case : puts("Bye!"); return ; break;
case :
printf("Enter a number: ");
scanf("%d", &number);
if(number<=)
printf("No negative factorial!\n");
else
printf("%d! = %lld\n", number, factorial(number));
break;
case :
printf("Enter a number: ");
scanf("%d", &number);
if(number<=)
printf("No negative fibonacci!\n");
else
fibonacci(, , number);
break;
}
} return ;
} void interface(void){
puts("+******************+");
puts("+ 0, quit +");
puts("+ 1, factorial +");
puts("+ 2, fibonacci +");
puts("+******************+");
}
/* 函数实现 */
long long factorial(int n){
/* 基线条件以及递归条件 */
if(n==)
return ;
else
return factorial(n-) * n;
}
void fibonacci(int x, int y, int stop){
if(x>stop){
printf("\n");
}else{
printf("%d ", x);
int tmp = y; y = x + y; x = tmp;
fibonacci(x, y, stop);
}
}