具有递归和While循环的指数兔子

几天前，我在这里问了一个关于Rabbits程序的问题，我几乎完成了它。问题是，当我输入0时，它崩溃了，无法运行。有人能帮我吗？这是我的任务：

一对刚出生的兔子(一只雄性，一只雌性)被放在田里。兔子能够在一个月大时交配，因此在第二个月底，每对兔子产下两对新兔子，然后死亡。注：在0月份，有0对兔子。在第一个月，有一对兔子。

1. 使用while循环编写一个程序，从用户那里获取月数，并在月底打印兔子对的数量
2. 在同一个cpp文件中，编写一个递归函数rabits()，该函数以月数为输入，并返回该月底兔子对的数量
3. 在主程序中，使用用户输入的数字调用函数rabits()。输出这两个计算(即您通过循环获得的计算和递归函数返回的计算)，看看它们是否相等

#include <iostream>
using namespace std;
int rabbits (int);
int main ()
{
int month_function, month_while, result_rec, result_while, counter = 0, rab_now, rab_lastmonth = 0, rab_twomonthsago = 1;
cout << "Please enter the month. nn";
cin >> month_function;
month_while = month_function;
cout << "n";
if (month_function % 2 == 0) // if month entered is even, the recursive function will use month - 1 because the total number of rabbits doubles every other month
{
month_function--;
}
result_rec = rabbits (month_function);
while (counter < month_while)
{
if (counter % 2 == 0)
{
rab_now = rab_lastmonth + rab_twomonthsago;
rab_lastmonth = rab_now;
rab_twomonthsago = rab_now;
}
counter++;
result_while = rab_lastmonth;
}
cout << "According to the recursive function, there are " << result_rec << " pairs of rabbits at the end of month " << month_while << "nn";
cout << "According to the while loop, there are " << result_while << " pairs of rabbits at the end of month " << month_while << endl;
if (result_rec = result_while)
{
cout << "n";
cout << "They are equal!" << endl;
}
else
{
cout << "They are not equal!" << endl;
}
return 0;
}
int rabbits (int month_function)
{
if (month_function == 0)
{
return 0;
}
else if (month_function == 1)
{
return 1;
}
else
{
return (rabbits (month_function - 2) + rabbits (month_function - 2));
}
}