Implementing a queue structure from scratch (C++) - c++

Question

I have to implement a queue from the scratch for an assignment without using any premade lib. It's working fine when I Enqueue e Dequeue, but when I Dequeue a unary queue (with just one element) and I print it, doesn't show that it is empty, the Print function actually print blank spaces, and when try to Enqueue new elements after Dequeuing the whole list it simply does not push new elements. Looks like that the reference to the first element got lost. If someone could help, here is the code:
structs:
typedef struct{
int number;
}TItem;
typedef struct cell{
struct cell *pNext;
TItem item;
}TCell;
typedef struct{
TCell *pFirst;
TCell *pLast;
}TQueue;
And the imlementations:
void Init(TQueue* pQueue){
pQueue->pFirst = new TCell;
pQueue->pLast = pQueue->pFirst;
pQueue->pFirst->pNext = NULL;
}
int Is_Empty(TQueue* pQueue){
return (pQueue->pFirst == pQueue->pLast);
}
int Enqueue(TQueue* pQueue, TItem x){
pQueue->pLast->pNext = new TCell;
pQueue->pLast = pQueue->pLast->pNext;
pQueue->pLast->item = x;
pQueue->pLast->pNext = NULL;
return 1;
}
int Dequeue(TQueue* pQueue, TItem* pX){
if(Is_Empty(pQueue))
return 0;
TCell* aux;
aux = pQueue->pFirst->pNext;
*pX = aux->item;
pQueue->pFirst->pNext = aux->pNext;
delete aux;
return 1;
}
void Print(TQueue* pQueue){
if(Is_Empty(pQueue) == 1)
cout << "EMPTY"<<endl;
TCell *temp;
temp = pQueue->pFirst->pNext;
cout << "Queue:"<<endl;
while( temp != NULL){
cout << temp->item.number << " ";
temp = temp->pNext;
}
}
PS: The memory allocation for the queue is made on the main block

Answer 1

Problem
Your Dequeue logic is invalid. All you need to do when dequeing is remove the first item in the queue.
Solution
int Dequeue(TQueue* pQueue, TItem* pX){
if(Is_Empty(pQueue))
return 0;
TCell* aux;
//aux = pQueue->pFirst->pNext;
aux = pQueue->pFirst;
//*pX = aux->item;
//pQueue->pFirst->pNext = aux->pNext;
pQueue->pFirst = aux->pNext;
delete aux;
return 1;
}
Also I don't know why you need to pass TItem* pX as you don't really use it.