Sample Queue C++

Sample Queue implementation in C++

#include<iostream>

//defining node data type
class node
{
    friend linkedqueue;//allowing linkedqueue class to access the data members of class node
    private:
    int data;//value field
    node *link;//address field
};

//defining class linkedqueue
class linkedqueue
{
    private:
    node *front;//pointer to first node
    node *rear;//pointer to last node
    public:
    linkedqueue();//constructor
    {
        front=rear=0;//initialising both front and rear to null
    }

    ~linkedqueue();//destructor
    bool isempty() //function to find out whether queue is empty
    {
        return(front)?false;true);//if front pointer is null, queue is empty
    }
    bool isfull();//checks whether queue is full
    int first();//returns first value stored
    int last();//returns last value stored
    linkedqueue& add(const int& x);//function to insert the new node at the end of the linked list
    linkedqueue& delete(int& x);//function to delete the first node
};

linkedqueue::~linkedqueue()//destructor function definition
{
    node *next;//create a dummy pointer to a node
    while(front)
    {
    next=front-->link;//destroy all the nodes of a queue
    delete front;
    front=next;
    }
}

bool linkedqueue::isfull()//isfull fucntion definition
//returns true if queue is full
{
    node *p;
    try
    {
    p=new node;//create a new dummy node,
    delete p;//delete the dummy node
    return false;
    }
    catch (noMem) {return true;}//if memory allocation was successful return false else return true
}

int linkedqueue::first()//first function definition
//returns the first value
{
    if(isempty())
    {
    cout<< "queue empty";
    return 0;
    }
    return front-->data;//if queue is not empty return first value
}

int linkedqueue::last()//last function definition
{
    if(isempty()
    {
    cout<< "queue empty";
    return 0;
    }
    return rear-->data;//if queue is not empty returns the last value
}

linkedqueue& linkedqueue::add(const int& x)//function to add new node at the end of the queue
//modifies the linked queue
{
    node *p= new node://creating a new node
    p-->data=x;//assigning the data value
    p-->link=0;//link points to null
    if(front) rear-->link=p;//if queue is not empty new node becomes the rear node of the queue
    else front=p;//if queue is empty ,new node corresponds to both front and rear node
    rear=p;
    return *this;
}

linkedqueue& linkedqueue::delete(int& x)//function to delete the first node of the queue
//modifies the linked queue
{

    x=front->data;
    node *p=front;
    front=front->link;//front points to next node
    delete p;//first node is deleted
    return *this;
}

int main()
{
linkedqueue queue;
int y
cout<<"enter the first value\n";
cin>>y;
queue.add(y);
cout<<"Enter the second value\n";
cin>>y;
queue.add(y);
cout<<"enter the third value\n";
cin>>y;
queue.add(y);
cout<<"first value:";
y=queue.first();
cout<<y;
cout<<"\nlast value:";
cout<<queue.last();
cout<<"\nafter pop operation";
queue.delete();
cout<<"first value:";
y=queue.first();
cout<<y;
cout<<"\nlast value:";
cout<<queue.last();
}

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