program received signal SIGFPE问题

Question

1.链队进行输出的时候出现program received signal SIGFPE问题，找了很久都无法
解决

#include<iostream>
using namespace std;
typedef int ElemType;

//创建链表的数据结点类型 
typedef struct Listnode
{
    ElemType data;
    Listnode *next;
}Listnode;

//创建链表结点类型 
typedef struct
{
    Listnode *front; //队头指针 --- 指向头结点 
    Listnode *rear;  //队尾指针 --- 指向尾结点 
}Sqnode;

//初始化链表
void Init_node(Sqnode *&q)
{
    q = new Sqnode;
    q->front = q->rear = NULL; // 因为队头就是链表的头结点，所以让其指向NULL，又因为队尾指向尾结点，此时头结点即是尾结点 
} 

//销毁链表
void Destroy_node(Sqnode *&q)
{
    Listnode *pre = q->front,*p;
    if(pre)
    {
        p = pre->next;
        while(p)
        {
            delete pre;
            pre = p;
            p = p->next;
        }
    }
    delete pre;
} 

//判断链表是否为空
bool Empty(Sqnode *q)
{
    return (q->rear == NULL);
} 

//进队
void Enter_Queue(Sqnode *&q,ElemType e)
{
    Listnode *pnew;       // 创建一个新的结点 
    pnew = new Listnode;
    pnew->data = e;       
    pnew->next = NULL;  //由于队列是队尾插入，所以新结点的下一个指向为空 
    if(Empty(q)) //若队列为空，则头结点即是尾结点即是pnew 
    {
        q->front = q->rear = pnew;
    }
    else
    {
        q->rear->next = pnew; // 若不为空，尾结点即是新的结点 
        q->rear = pnew;
    }
} 

//出队 --- 队头出 --- 所以首结点出队 
bool De_Queue(Sqnode *&q,ElemType &e)
{
    Listnode *p; 
    if(Empty(q)) // 若链表为空，没有结点，返回假 
    {
        return false;
    }
    p = q->front; //先让辅助指针指向头结点 
    if(q->front == q->rear) //若只有一个结点即头结点，指向空即可 
    {
        q->front = q->rear = NULL;
    }
    else
    {
        q->front = q->front->next; // 首结点出队 
        e = p->data;
        delete p;
        return true;
    }
} 

//遍历所有结点
void display(Sqnode *q)
{
    Listnode *p;
    if(Empty(q))
    {
        return;
    }
    else
    {
        p = q->front;
        while(p != NULL)
        {
            p = p->next;
            cout << p->data << " ";
        } 
    }
} 

int main(void)
{
    Sqnode *q;
    Init_node(q);
    int choice;
    while(1)
    {
        cout << "1.排队 2.就诊 3.查看排队 4.下班 请选择:";
        cin >> choice;
        switch(choice)
        {
            case 1:
                ElemType e;
                cout << "----->>请输入病历号:";
                cin >> e;
                Enter_Queue(q,e);
                cout << "排队的病人依次是:";
                display(q);
                cout << endl << endl; 
                break;
            //case 2:

        }
    }
    return 0;
}

求求各位大神帮助一下，谢谢了

Answer 1

void display(Sqnode* q)
{
    Listnode* p;
    if (Empty(q))
    {
        return;
    }
    else
    {
        p = q->front;
        while (p != NULL)
        {
            cout << p->data << " ";
            p = p->next;
        }
    }
}