My implementation of the queue data structure

queue.cpp

#include <iostream>

using namespace std;


template <class T>
class Queue
{
    struct Node
    {
        T value;
        Node *next = NULL;
    };

    Node *front, *rear;
    int length = 0;
public:
    Queue() : front(nullptr), rear(nullptr) {}

    ~Queue() {
        this->clear();
    }

    bool isEmpty()
    {
        return (this->rear == NULL);
    }

    void enqueue(T v) {
        Node *tmp = new Node;
        if (tmp == NULL)
            cout << "Stack::push(T v) can't allocate memory\n";
        else {
            ++length;
            if(isEmpty()){
                front = new Node;
                front->value = v;
                front->next = NULL;
                rear = front;
            }
            else{
                Node* tmp = new Node;
                tmp->value = v;
                tmp->next = NULL;
                rear->next = tmp;
                rear = tmp;
            }
        }
    }

    void dequeue(){
        if (isEmpty()) {
            cout << "Can't dequeue an empty queue" << endl;
        }
        else {
            if(length == 1){
                front->next = NULL;
                front = rear = NULL;
            }
            else{
                Node* tmp = front;
                front = front->next;
                tmp->next = NULL;
                delete tmp;
                }
            --length;
        }
    }

    T getFront()
    {
        if (isEmpty())
        {
            cout << "can't getTop() an empty stack\n";
            return -1;
        }
        else
            return front->value;
    }

    T getRear()
    {
        if (isEmpty())
        {
            cout << "can't getTop() an empty stack\n";
            return -1;
        }
        else
            return rear->value;
    }

    void clear()
    {
        if (isEmpty())
            return;
        else
        {
            Node *tmp;
            while (front != NULL)
            {
                tmp = front;
                front = front->next;
                tmp->next = NULL; // for safty reasons
                delete tmp;
            }
            rear = NULL;
        }
    }

    void disp()
    {
        Node *cur = front;
        cout << '[';
        while (cur != NULL)
        {
            cout << cur->value << " ";
            cur = cur->next;
        }
        cout << ']';
    }
};

int main()
{
    Queue<int> q;
    q.enqueue(2);
    q.enqueue(4);
    q.enqueue(6);
    q.enqueue(8);
    q.enqueue(10);
    q.enqueue(12);
    // q.disp();
    // cout << q.getFront() << ',' << q.getRear();
    q.enqueue(14);
    q.clear();
    q.disp();
    return 0;
}