引发了未经处理的异常:读取访问权限冲突。 **this** 是 nullptr。

 ```c++
#include 
#include 
#include
using namespace std;
template<class ElemType>
struct Node
{
    ElemType data;//数据
    struct Node* next;//后继指针
};
template<class ElemType>
class Queue
{
public:
    Node* tail;//尾指针
public:
    Queue();
    bool InQueue(ElemType x);
    bool OutQueue();
    bool GetHead();
};
template<class ElemType>
Queue::Queue()
{
    Queue* queue = new Queue;
        //malloc(sizeof(Queue));
    Node* node = new Node;
        //malloc(sizeof(Node));
    queue->tail = node;
    queue->tail->nex = queue->tail;//指向自己
    return queue;
}
template<class ElemType>
bool Queue::InQueue(ElemType x)
{
    
    Node* p = new Node;
        //malloc(sizeof(Node));
    p->data = x;
    p->next = this->tail->next;
    this->tail->next = p;
    this->tail = p;
    return true;
}
template<class ElemType>
bool Queue::OutQueue()
{
    Node* node;
    node = this->tail->next->next;
    if (this->tail->next->next == this->tail->next)
    {
        cout << "队列为空" << endl;
        return false;//判断为空
    }
    ElemType x = node->data;
    if (node == this->tail)//只有一个结点
    {
        this->tail = this->tail->next;
        this->tail->next = this->tail;
    }
    else
        this->tail->next->next = node->next;
    free(node);//清除数据
    cout << "删除数据为:" << x << endl;
    return true;

}
template<class ElemType>
bool Queue::GetHead()
{
    Node* node;
    node = this->tail->next->next;
    if (this->tail->next->next == this->tail->next)
    {
        cout << "队列为空" << endl;
        return false;//判断为空
    }
    ElemType x = node->data;
    cout << "队头数据为" << x << endl;
    return true;
}
int main()
{
    Queue<int>* queue=NULL;
    queue->InQueue(1);
    queue->OutQueue();
    queue->GetHead();

}

![img](https://img-mid.csdnimg.cn/release/static/image/mid/ask/743944322366142.jpg "#left")

Queue<int>* queue=NULL;
    queue->InQueue(1);

这一看就不对啊，queue等于NULL了，怎么能进行指针操作呢？？？不要用指针