Queue Implementation Using Linked List or Pointer

PROGRAM:

#include<stdio.h>

#include<conio.h>

typedef struct queue

{

                int data;

                struct queue *next;

}node;

node *newn,*front,*rear,*temp;

void enqueue();

void dequeue();

void display();

void main()

{

                int ch;

                clrscr();

                printf("\n\n\n$$$ QUEUE IMPLEMENTATION USING LINKED LIST OR POINTER $$$\n\n\n");

                while(1)

                {

                                printf("QUEUE OPERATIONS ARE\n");

                                printf("1.ENQUEUE\n2.DEQUEUE\n3.DISPLAY\n4.EXIT\n");

                                printf("Enter your choice:\t");

                                scanf("%d",&ch);

                                switch(ch)

                                {

                                                case 1:enqueue();break;

                                                case 2:dequeue();break;

                                                case 3:display();break;

                                                case 4:exit(0);

                                                default:printf("Enter the correct option\n");

                                                break;

                                }

                }

}

void enqueue()

{

                newn=(node *)malloc(sizeof(node));

                printf("Enter the element to be inserted:\t");

                scanf("%d",&newn->data);

                newn->next=NULL;

                if(front==NULL)

                {

                                front=newn;

                                rear=newn;

                }

                else

                {

                                rear->next=newn;

                                rear=newn;

                }

}

void dequeue()

{

                if(front==NULL)

                {

                                printf("Queue is empty or underflow\n");

                }

                else

                {

                                temp=front;

                                front=front->next;

                                printf("The deleted element is: %d",temp->data);

                }

                free(temp);

}

void display()

{

                if(front==NULL)

                {

                                printf("Queue is empty or underflow\n");

                }

                else

                {

                                temp=front;

                                printf("Content of the queue is:\n");

                                while(temp!=NULL)

                                {

                                                printf("%d\n",temp->data);

                                                temp=temp->next;

                                }

                }

}

 OUTPUT:

$$$ QUEUE IMPLEMENTATION USING LINKED LIST OR POINTER $$$

 QUEUE OPERATIONS ARE

1.ENQUEUE

2.DEQUEUE

3.DISPLAY

4.EXIT

Enter your choice:      1

Enter the element to be inserted:       11

QUEUE OPERATIONS ARE

1.ENQUEUE

2.DEQUEUE

3.DISPLAY

4.EXIT

Enter your choice:      1

Enter the element to be inserted:       22

QUEUE OPERATIONS ARE

1.ENQUEUE

2.DEQUEUE

3.DISPLAY

4.EXIT

Enter your choice:      1

Enter the element to be inserted:       33

QUEUE OPERATIONS ARE

1.ENQUEUE

2.DEQUEUE

3.DISPLAY

4.EXIT

Enter your choice:      3

Content of the queue is:

11

22

33

QUEUE OPERATIONS ARE

1.ENQUEUE

2.DEQUEUE

3.DISPLAY

4.EXIT

Enter your choice:      2

The deleted element is: 11

QUEUE OPERATIONS ARE

1.ENQUEUE

2.DEQUEUE

3.DISPLAY

4.EXIT

Enter your choice:           3

Content of the queue is:

22

33

QUEUE OPERATIONS ARE

1.ENQUEUE

2.DEQUEUE

3.DISPLAY

4.EXIT

Enter your choice:      4