• 递归实现

int View::fibRecursively(int n)
{
    int ret = 0;
    if(n <= 0)
    {
        ret = 0;
    }else if(n == 1 || n == 2)
    {
        ret = 1;
    }else{
        ret = fibRecursively(n-1) + fibRecursively(n-2);
    }

    return ret;
}

• 循环实现

int View::fib(int n)
{
    int ret = 0;
    int nextItem = 1;

    if(n <= 0)
    {
        ret = 0;
    }else{
        for(int i = 1 ; i <= n ; ++i)
        {
            int tmp = nextItem;
            nextItem += ret;
            ret = tmp;
        }
    }

    return ret;
}