Question

How do I pass values to this function?

class DynIntQueue
{
    struct QueueNode
    {
        int value;
        QueueNode *next;
        QueueNode(int value1, QueueNode *next1 = nullptr)
        {
            value = value1;
            next = next1;
        }
    };
    // These track the front and rear of the queue
    QueueNode *front;
    QueueNode *rear;
public:
    // Constructor and Destructor
    DynIntQueue();
    ~DynIntQueue();

    // Member functions
    void enqueue(int);
    void dequeue(int &);
    bool isEmpty() const;
    void clear();
};

main

#include <iostream>
#include "DynIntQueue.h"
using namespace std;
int main()
{DynIntQueue list;

    list.enqueue(32);
    list.enqueue(&num);//this member function call seems to be causing issues.
   // list.isEmpty();
    list.clear();

    //Pause the program until input is received
int num=1;
    return 0;
}

cpp

DynIntQueue::DynIntQueue()
{
    front = nullptr;
    rear = nullptr;
}

//************************
// Destructor.           *
//************************
DynIntQueue::~DynIntQueue()
{
    QueueNode * garbage = front;
    while (garbage != nullptr)
    {
        front = front->next;
        garbage->next = nullptr;
        delete garbage;
        garbage = front;
    }
}

//********************************************
// Function enqueue inserts the value in num *
// at the rear of the queue.                 *
//********************************************
void DynIntQueue::enqueue(int num)
{
    if (isEmpty())
    {
        front = new QueueNode(num);
        rear = front;
    }
    else
    {
        rear->next = new QueueNode(num);
        rear = rear->next;
    }
}

//**********************************************
// Function dequeue removes the value at the   *
// front of the queue, and copies it into num. *
//**********************************************
void DynIntQueue::dequeue(int &num)
{
    QueueNode *temp = nullptr;
    if (isEmpty())
    {
        cout << "The queue is empty.\n";
        exit(1);
    }
    else
    {
        num = front->value;
        temp = front;
        front = front->next;
        delete temp;
    }
}

//*********************************************
// Function isEmpty returns true if the queue *
// is empty, and false otherwise.             *
//*********************************************
bool DynIntQueue::isEmpty() const
{
    if (front == nullptr)
        return true;
    else
        return false;
}

//********************************************
// Function clear dequeues all the elements  *
// in the queue.                             *
//********************************************
void DynIntQueue::clear()
{
    int value;   // Dummy variable for dequeue

    while (!isEmpty())
        dequeue(value);
}

Answer 1

#######################################
     DynIntQueue.cpp
#######################################
#include "DynIntQueue.h"

DynIntQueue::DynIntQueue()
{
    front = nullptr;
    rear = nullptr;
}

//************************
// Destructor.           *
//************************
DynIntQueue::~DynIntQueue()
{
    QueueNode * garbage = front;
    while (garbage != nullptr)
    {
        front = front->next;
        garbage->next = nullptr;
        delete garbage;
        garbage = front;
    }
}

//********************************************
// Function enqueue inserts the value in num *
// at the rear of the queue.                 *
//********************************************
void DynIntQueue::enqueue(int num)
{
    if (isEmpty())
    {
        front = new QueueNode(num);
        rear = front;
    }
    else
    {
        rear->next = new QueueNode(num);
        rear = rear->next;
    }
}

//**********************************************
// Function dequeue removes the value at the   *
// front of the queue, and copies it into num. *
//**********************************************
void DynIntQueue::dequeue(int &num)
{
    QueueNode *temp = nullptr;
    if (isEmpty())
    {
        cout << "The queue is empty.\n";
        exit(1);
    }
    else
    {
        num = front->value;
        temp = front;
        front = front->next;
        delete temp;
    }
}

//*********************************************
// Function isEmpty returns true if the queue *
// is empty, and false otherwise.             *
//*********************************************
bool DynIntQueue::isEmpty() const
{
    if (front == nullptr)
        return true;
    else
        return false;
}

//********************************************
// Function clear dequeues all the elements  *
// in the queue.                             *
//********************************************
void DynIntQueue::clear()
{
    int value;   // Dummy variable for dequeue

    while (!isEmpty())
        dequeue(value);
}




#######################################
       DynIntQueue.h
#######################################
#include<iostream>
#include<cstdlib>

using namespace std;

class DynIntQueue
{
    struct QueueNode
    {
        int value;
        QueueNode *next;
        QueueNode(int value1, QueueNode *next1 = nullptr)
        {
            value = value1;
            next = next1;
        }
    };
    // These track the front and rear of the queue
    QueueNode *front;
    QueueNode *rear;
public:
    // Constructor and Destructor
    DynIntQueue();
    ~DynIntQueue();

    // Member functions
    void enqueue(int);
    void dequeue(int &);
    bool isEmpty() const;
    void clear();
};



#######################################
            main.cpp
#######################################
#include <iostream>
#include "DynIntQueue.h"
using namespace std;
int main()
{
        DynIntQueue list;

        cout << "Enqueuing the nummber 32." << endl;
        list.enqueue(32);

        // declare a variable in which dequeued data from the 
        // queue will be filled in.
        int num;

        // pass num to function, the function fills the value
        list.dequeue(num);

        // print the filled data
        cout << "Dequeued number: " << num << endl;

        // list.isEmpty();
        list.clear();


        return 0;
}


i have given comments to make you understand on whats happening.. If still any issues, please ask in comments. If you find it helpful, please upvote.