Queue Program in C++

This C++ Program demonstrates operations on Queue.

Here is source code of the C++ Program to demonstrate Queue operations using linked list. The C++ program is successfully compiled and run on a Linux system. The program output is also shown below.

```
/*
```

 * C++ Program To Implement Queue using Linked List

```
 */
```
```
#include<iostream>
```
```
#include<cstdlib>
```
```
using namespace std;
```
```
 
```
```
/*
```
```
 * Node Declaration
```
```
 */
```
```
struct node
```
```
{
```
```
    int info;
```
```
    struct node *link;    
```
```
}*front, *rear;
```
```
 
```
```
/*
```
```
 * Class Declaration
```
```
 */
```
```
class queue_list
```
```
{
```
```
    public:
```
```
        void insert(int);
```
```
        void display();
```
```
        void del();
```
```
        queue_list()
```
```
        {
```
```
            front = NULL;
```
```
            rear = NULL;
```
```
        }               
```
```
};
```
```
 
```
```
/*
```
```
 * Main: Contains Menu
```
```
 */
```
```
int main()
```
```
{
```
```
    int choice, item;
```
```
    queue_list ql;
```
```
    while (1)
```
```
    {
```
```
        cout<<"\n-------------"<<endl;
```

        cout<<"Operations on Queue"<<endl;

```
        cout<<"\n-------------"<<endl;
```

        cout<<"1.Insert Element into the Queue"<<endl;

        cout<<"2.Delete Element from the Queue"<<endl;

        cout<<"3.Traverse the Queue"<<endl;

```
        cout<<"4.Quit"<<endl;
```
```
        cout<<"Enter your Choice: ";
```
```
        cin>>choice;
```
```
        switch(choice)
```
```
        {
```
```
        case 1:
```

            cout<<"Enter value to be inserted into the queue: ";

```
            cin>>item;
```
```
            ql.insert(item);
```
```
            break;
```
```
        case 2:
```
```
            ql.del();
```
```
            break;
```
```
        case 3:
```
```
            ql.display();
```
```
            break;
```
```
        case 4:
```
```
            exit(1);
```
```
            break;
```
```
        default:
```
```
            cout<<"Wrong Choice"<<endl;
```
```
        }
```
```
    }
```
```
    return 0;
```
```
}
```
```
 
```
```
/*
```
```
 * Insert Element into the Queue
```
```
 */
```
```
void queue_list::insert(int item)
```
```
{
```
```
    node *tmp;
```
```
    tmp = new (struct node);
```
```
    tmp->info = item;
```
```
    tmp->link = NULL;
```
```
    if (front == NULL)
```
```
        front = tmp;
```
```
    else
```
```
        rear->link = tmp;
```
```
    rear = tmp;
```
```
}
```
```
 
```
```
/*
```
```
 * Delete Element from the Queue
```
```
 */
```
```
void queue_list::del()
```
```
{
```
```
    node *tmp;
```
```
    if (front == NULL)
```
```
        cout<<"Queue Underflow"<<endl;
```
```
    else
```
```
    {       
```
```
        tmp = front;
```

        cout<<"Element Deleted: "<<tmp->info<<endl;

```
        front = front->link;
```
```
        free(tmp);
```
```
    }
```
```
}
```
```
 
```
```
/*
```
```
 * Traversing the Stack
```
```
 */
```
```
void queue_list::display()
```
```
{       
```
```
    node *ptr;
```
```
    ptr = front;
```
```
    if (front == NULL)
```
```
        cout<<"Queue is empty"<<endl;
```
```
    else
```
```
    {
```
```
        cout<<"Queue elements :"<<endl;
```
```
        while (ptr != NULL)
```
```
        {
```
```
            cout<<ptr->info<<" ";
```
```
            ptr = ptr->link;
```
```
        }
```
```
        cout<<endl;
```
```
    }
```
```
}
```

$ g++ queue.cpp
$ a.out
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 3
Queue is empty
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 2
Queue Underflow
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 1
Enter value to be inserted into the queue: 100
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 3
Queue elements :
100 
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 1
Enter value to be inserted into the queue: 200
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 3
Queue elements :
100 200 
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 1
Enter value to be inserted into the queue: 150
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 3
Queue elements :
100 200 150 
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 1
Enter value to be inserted into the queue: 50
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 3
Queue elements :
100 200 150 50 
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 2
Element Deleted: 100
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 3
Queue elements :
200 150 50 
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 2
Element Deleted: 200
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 3
Queue elements :
150 50 
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 1
Enter value to be inserted into the queue: 1010
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 3
Queue elements :
150 50 1010 
 
-------------
Operations on Queue
 
-------------
1.Insert Element into the Queue
2.Delete Element from the Queue
3.Traverse the Queue
4.Quit
Enter your Choice: 4
 
 
------------------
(program exited with code: 1)
Press return to continue

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