Queue Implementation Using Array & Linked List
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This document describes two implementations of a queue data structure in C++. A queue uses the First In First Out (FIFO) principle to add and remove elements. Elements can be added to the rear of the queue using the Enque operation and removed from the front using the Deque operation. The first implementation uses an array to store queue elements, while the second uses linked nodes to dynamically allocate memory for elements as they are added. Both implementations provide functions for Enqueuing, Dequeuing, checking if the queue is empty, and displaying the queue elements.
![Queue::Queue()
{
cout<<"Enter size : ";
cin>>size;
array=new int[size];
f=r=-1;
count=0;
}](https://image.slidesharecdn.com/queue-140611015517-phpapp02/85/Queue-Implementation-Using-Array-Linked-List-4-320.jpg)
![void Queue::Enque(int value)
{
if(!is_Full())
{
array[++r]=value;
count++;
}
else
{
cout<<"nnOverFlow ! nn";
}
}](https://image.slidesharecdn.com/queue-140611015517-phpapp02/85/Queue-Implementation-Using-Array-Linked-List-5-320.jpg)
![int Queue::Deque()
{
if(!is_Empty())
{
count--;
return array[++f];
}
else
{
cout<<"nnUnderFlow ! nn";
}
}](https://image.slidesharecdn.com/queue-140611015517-phpapp02/85/Queue-Implementation-Using-Array-Linked-List-6-320.jpg)
Queue Implementation Using Array & Linked List
- 2. Two Basic Operations in Queue Enque : Inserting new element from rear end Deque : Removing existing element from front end Front End Rear End 0 1 2 3 4 5 6
- 3. #include <iostream> using namespace std; class Queue { int* array,size,f,r,count; public: Queue(); void Enque(int value); int Deque(); bool is_Empty(); bool is_Full(); };
- 4. Queue::Queue() { cout<<"Enter size : "; cin>>size; array=new int[size]; f=r=-1; count=0; }
- 5. void Queue::Enque(int value) { if(!is_Full()) { array[++r]=value; count++; } else { cout<<"nnOverFlow ! nn"; } }
- 6. int Queue::Deque() { if(!is_Empty()) { count--; return array[++f]; } else { cout<<"nnUnderFlow ! nn"; } }
- 7. bool Queue::is_Empty() { return f==r==-1; } bool Queue::is_Full() { return count==size; }
- 8. void main() { Queue obj; obj.Enque(1); obj.Enque(2); obj.Enque(3); obj.Deque(); } 1 2 3 0 1 2 3 4 5 6
- 10. #include <iostream> using namespace std; class Node { int value; Node*next; friend class Queue; public: Node() { next=NULL; } };
- 11. class Queue { Node *first,*last; public: Queue() { first=last=NULL; } void Enque(int v); bool is_Empty(); void Deque(); void Display(); }; first last
- 12. void Queue::Enque(int v) { Node *n=new Node(); n->value=v; if(first==NULL) { last=first=n; } else { last->next=n; last=n; } } DATA NEXT
- 13. void Queue::Deque() { if(!is_Empty()) { Node *temp=first; first=first->next; cout<<"nnThe data Dequeued is : "<<temp->value<<endl; delete temp; } }
- 15. void Queue::Display() { Node *p = new Node; p = first; cout<<"nnQueue Elements are : nn"; while(p!=NULL) { cout<<p->value<<endl; p = p->next; } }
- 16. Void main() { Queue Q; Q.Enque(12); Q.Enque(15); Q. Deque(); Q .Display(); } 100 200 12 15 200 NULL 100 200 first last 200