Data Structure Queue Implementation of Linked List in C++

[+] Post Title :

Data Structure Queue Implementation of Linked List in C++

[+] Date : Sunday, 20 October 2013
[+] Author : Prudhvi raj
[+] Type : Queue L L

Algorithm

1. Declare and initialize necessary variables such as struct node *front, *rear etc
2. For enqueue operation,
    -take input data to be inserted
    -create an empty node and assign data to its into field
     i.e. p->info=data
           p->next = NULL
           if front = NULL
             front = p
           else
              rear->next = p
    -rear = p
3. For next enqueue operation, goto step 2
4. For dequeue operation, 
      if front = NULL
        print "Queue is empty"
      else
         -create a node pointer temp
         -temp = front
         -front = front->next
         -display dequeued item as temp->data
         -delete temp
5. For dequeue of next data item, goto step 4

Program:- 

#include<iostream>
#include<cstdlib>
using namespace std;
struct node{
    int info;
    struct node *next;
};
class Queue{
    private:
        node *rear;
        node *front;
    public:
        Queue();
        void enqueue();
        void dequeue();
        void display();
};
Queue::Queue(){
    rear = NULL;
    front = NULL;
}
void Queue::enqueue(){
    int data;
    node *temp = new node;
    cout<<"Enter the data to enqueue: ";
    cin>>data;
    temp->info = data;
    temp->next = NULL;
    if(front == NULL){
        front = temp;
    }else{
        rear->next = temp;
    }
    rear = temp;
}
void Queue::dequeue(){
    node *temp = new node;
    if(front == NULL){
        cout<<"\nQueue is Emtpty\n";
    }else{
        temp = front;
        front = front->next;
        cout<<"The data Dequeued is "<<temp->info;
        delete temp;
    }
}
void Queue::display(){
    node *p = new node;
    p = front;
    if(front == NULL){
        cout<<"\nNothing to Display\n";
    }else{
        while(p!=NULL){
            cout<<endl<<p->info;
            p = p->next;
        }
    }
}
int main(){
    Queue queue;
    int choice;
    while(true){
        cout<<"\n1.Enqueue\n2. Dequeue\n3. Display\n 4.Quit";
        cout<<"\nEnter your choice: ";
        cin>>choice;
        switch(choice){
            case 1:
                queue.enqueue();
                break;
            case 2:
                queue.dequeue();
                break;
            case 3:
                queue.display();
                break;
            case 4:
                exit(0);
                break;
            default:
                cout<<"\nInvalid Input. Try again! \n";
                break;
        }
    }
    return 0;
}