Moving data from one queue to another queue

Question

I dequeue a queue and if the employee's salary is less than 50,000. I am not sure how to enqueue it into another queue as my enqueue function takes three parameters. My assignment says to create a class and then two queues in main. I made the queues being an object of the class, is this correct? How do I enqueue into the second queue with only having one enqueue function in the class which takes three parameters. Thanks for all the help.

#include <cstdlib>
#include <iostream>
#include <string>
#include <iomanip>
using std::cout;
using std::cin;
using std::endl;
using std::string;
using std::fixed;
using std::setprecision;

struct node{
    string name;
    int id;
    int salary;
    struct node *next;
};

node *rear;
node *front;

class DynEmpQueue{
private:
    int counter = 0;
public:
    void enqueue(string, int, int);
    void dequeue();
    void traverse()const;
    DynEmpQueue()
    {
        rear = nullptr;
        front = nullptr;
        counter = 0;
    }
};

void DynEmpQueue::enqueue(string localName, int localID, int localSalary)
{
    node *temp;
    temp = new (struct node);
    temp -> name = localName;
    temp -> id = localID;
    temp -> salary = localSalary;
    temp -> next = nullptr;
    if (front == nullptr)
        front = temp;
    else
        rear -> next = temp;
    rear = temp;
    counter++;
}

void DynEmpQueue::dequeue()
{
    string localName;
    int localID;
    int localSalary;
    node *temp;
    if (front == nullptr)
        cout << "The queue is empty.";
    else
    {
        temp = front;
        localName = temp -> name;
        localID = temp -> id;
        localSalary = temp -> salary;
        front = front -> next;
        delete temp;
        counter--;
    }
}

void DynEmpQueue::traverse()const
{
    node *temp;
    temp = front;
    if (front == nullptr)
        cout << "Queue is empty.";
    else
    {
        cout << "Queue contains " << counter << " elements." << endl;
        cout << "Queue elements:" << endl;
        while (temp != nullptr)
        {
            cout << temp -> name << "\t" << temp -> id << "\t" << temp -> salary << endl;
            temp = temp -> next;
        }
    }
}

int main()
{
    const int NumberEmployees = 5;
    DynEmpQueue originalQueue;

    originalQueue.enqueue("Justin Gray", 100, 104000);
    originalQueue.enqueue("Mike Smith", 200, 207000);
    originalQueue.enqueue("Jose Cans", 400, 47000);
    originalQueue.enqueue("Auston Matts", 300, 31000);
    originalQueue.enqueue("Liz Learnerd", 600, 89100);

    node object;
    DynEmpQueue demandSalaryIncrease;

    for (int i = 0; i < NumberEmployees; i++)
    {
        originalQueue.dequeue();
        if (object.salary <= 50000)
            demandSalaryIncrease.enqueue();
    }

    demandSalaryIncrease.traverse();

    return 0;
}

Answer 1

You cannot know what employees exist in your queue. Look at how you defined your methods:

void enqueue(string, int, int);
void dequeue();
void traverse() const;

As you can see, no method returns either a node or the employee's data. So, as you currently declared the class, there is no way to get employees from your queue. And, since you can't even get employees are in the queue, you cannot add them into another queue.

Possible solution:

Modify your traverse() method so that it takes a salary as argument and returns an array (or even a queue) containing all the employees for which the salary is lower than that salary.

A better and much more flexible solution would be to use a predicate, but (since you are using global variables) it seems like you're not looking for perfect solutions anyway.