Queue implementation

[VanKha]

I write a queue program but it doesn't work properly:I enqueue an element and dequeue just after that, but the output is the first value and then many times of "Empty queue.."!Why ?Please help me.

#include<iostream>
#include<conio.h>
using namespace std;
class Node{
private:
    int value;
    Node * next;
public:
    Node(int n)
    {
        value=n;
        next=NULL;
    }
    int getValue(){ return value;}
    void setValue(int n) { value=n;}
    Node *getNext(){ return next;}
    void setNext(Node *nx){ next=nx;}
};
class Queue{
private:
    Node *front;
    Node *back;
    int size;
public:
    Queue();
    ~Queue();
    int Size(){ return size;}
    void enqueue(int n);
    int dequeue();
};
Queue::Queue()
{
    front=back=(Node *)NULL;
    size=0;
}
void Queue::enqueue(int n)
{
    if(back){
        Node *tmp=new Node(n);
        back->setNext(tmp);
        back=back->getNext();
    }
    else{
        front=back=new Node(n);
    }
    size++;
}
int Queue::dequeue()
{
    int x;
    if(front){
         x=front->getValue();
        Node *tmp=front;
        front=front->getNext();
        delete tmp;
        size--;
        return x;
 
    }
    else{
        cout<<"Empty queue:cannot dequeue!!";
        return -1;
    }
}
Queue::~Queue()
{
    int m;
    while(front)
         m=dequeue();
 
}
main()
{
    Queue IntQueue;
    for(int l=1;l<=5;l++){
 
        IntQueue.enqueue(l);
        cout<<"Current size:"<<IntQueue.Size()<<";value in front of queue :"<<IntQueue.dequeue()<<endl;
        cout<<"        Current size:"<<IntQueue.Size()<<endl;
        }
 
 
 
    getch();
}
 

[scruggsy]

When you dequeue the only element in the queue, front gets set to NULL via front=front->getNext. But you need to reset back to NULL at that same time, otherwise enqueue() adds the next node to the non-existent back node.