C Program For DeQueue using Doubly Linked List

 

C PROGRAM FOR DEQUEUE USING DOUBLY LINKED LIST

CODE

#include<stdio.h>

#include<stdlib.h>

struct Node *front=NULL;

struct Node *rear=NULL;

struct Node

{

int data;

struct Node *next;

struct Node *previous;

};

void traversal(struct Node *ptr)

{

printf("Elements in the queue after operations are\n");

while(ptr!=NULL)

{

printf("Element: %d\n",ptr->data);

ptr=ptr->next;

}

}

void frontEnqueue(int value)

{

struct Node *n=(struct Node *)malloc(sizeof(struct Node));

n->data=value;

if(n==NULL)

printf("Cannot insert from front end\n");

else if(front==NULL)

{

front=rear=n;

printf("Value enqueued at front is %d\n",value);

}

{

n->next=front;

front->previous=n;

front=n;

printf("Value enqueued at front is %d\n",value);

}

}

void frontDequeue()

{

if(front==NULL)

printf("Queue is empty\n");

else

{

int value;

struct Node *ptr=front;

value=ptr->data;

front=front->next;

front->previous=NULL;

free(ptr);

printf("The value dequeued from front is %d\n",value);

}

}

void rearEnqueue(int value)

{

struct Node *n=(struct Node*)malloc(sizeof(struct Node));

if(n==NULL)

printf("Overflow\n");

else

{

n->data=value;

n->next=NULL;

if(front==NULL)

{

front=rear=n;

printf("Value enqueued at rear is %d\n",value);

}

else

{

rear->next=n;

n->previous=rear;

rear=n;

printf("Value enqueued at rear is %d\n",value);

}

}

}

void rearDequeue()

{

if(front==NULL)

printf("Queue is empty\n");

else

{

int value;

struct Node *ptr=rear;

value=ptr->data;

rear=rear->previous;

rear->next=NULL;

free(ptr);

printf("The value dequeued from rear is %d\n",value);

}

}

int main()

{

rearEnqueue(10);

rearEnqueue(20);

frontEnqueue(40);

frontEnqueue(89);

frontDequeue();

rearEnqueue(50);

rearEnqueue(70);

rearDequeue();

frontDequeue();

frontDequeue();

rearEnqueue(440);

frontEnqueue(480);

rearEnqueue(500);

rearDequeue();

traversal(front);

return 0;

}

OUTPUT