链式存储队列

#include <iostream>
#include <assert.h>
using namespace std;
typedef struct node
{
    int data;
    struct node *next;
}NODE;
typedef struct queue
{
    NODE* head;
    NODE* tail;
}QUEUE;
QUEUE* create_queue()
{
    QUEUE* queue =  new QUEUE;
    queue->head = NULL;
    queue->tail = NULL;
    return queue;
}
NODE* create_node(int data)
{
    NODE* node = new NODE;
    node->data = data;
    node->next = NULL;
    return node;
}
void queue_push(QUEUE* queue,int data)
{
    NODE* node = create_node(data);
    if(queue->tail == NULL)
    {
        queue->tail = node;
        queue->head = node;
    }
    else
    {
        queue->tail->next = node;
        queue->tail = node;
    }
}
NODE* destroy_node(NODE* node)
{
    NODE* next = node->next;
    delete node;
    return next;
}
int queue_pop(QUEUE* queue)
{
    if(queue->head == NULL)
    {
        assert(false);
    }
    int data = queue->head->data;
    queue->head =destroy_node(queue->head);
    if(queue->head == NULL)
    {
        queue->tail = NULL;
    }
    return data;
}
int queue_size (QUEUE* queue)
{
    int size = 0;
    NODE* node = NULL;
    for(node=queue->head; node;node=node->next)
    {
        size++;
    }
    return size;
}
void clear(QUEUE* queue)
{
    while(queue->head)
    {
        queue->head = destroy_node(queue->head);
    }
    queue->tail = NULL;
}
void destroy_queue(QUEUE* queue)
{
    clear(queue);
    delete queue;
}
bool queue_empty(QUEUE* queue)
{
    if( (queue->head==NULL) && (queue->tail==NULL))
    {
        return true;
    }
    return false;
}

int main()
{
    QUEUE* queue = create_queue();
    cout<<"input number:  ";
    for(int i=0;i<10;i++)
    {
        queue_push(queue,i);
        cout<<i<<" ";
    }
    cout<<endl;
    //queue_pop(queue);  //
    cout<<"output number:";
    while(! queue_empty(queue))
    {
        cout<<queue_pop(queue)<<" ";
    }
    cout<<endl;
    destroy_queue(queue);
    return 0;
}