IMPLEMENTATION OF QUEUE USING ARRAY AND LINKED LIST

#include<stdio.h>

#include<conio.h>

#define MAX 50

int queue_array[MAX];

int rear = - 1;

int front = - 1;

void main()

{

    int choice;

    void insert();

    void delete();

    void display();

    while (1)

    {

printf("1.Insert element to queue \n");

printf("2.Delete element from queue \n");

printf("3.Display all elements of queue \n");

printf("4.Quit \n");

printf("Enter your choice : ");

scanf("%d", &choice);

switch (choice)

{

   case 1:

   insert();

   break;

   case 2:

   delete();

   break;

   case 3:

   display();

   break;

   case 4:

   exit(1);

   default:

   printf("Wrong choice \n");

} /*End of switch*/

    } /*End of while*/

} /*End of main()*/

void insert()

{

    int add_item;

    if (rear == MAX - 1)

    printf("Queue Overflow \n");

    else

    {

if (front == - 1)

/*If queue is initially empty */

front = 0;

printf("Insert the element in queue : ");

scanf("%d", &add_item);

rear = rear + 1;

queue_array[rear] = add_item;

    }

} /*End of insert()*/

void delete()

{

    if (front == - 1 || front > rear)

    {

printf("Queue Underflow \n");

return ;

    }

    else

    {

printf("Element deleted from queue is : %d\n", queue_array[front]);

front = front + 1;

    }

} /*End of delete() */

void display()

{

    int i;

    if (front == - 1)

printf("Queue is empty \n");

    else

    {

printf("Queue is : \n");

for (i = front; i <= rear; i++)

   printf("%d ", queue_array[i]);

printf("\n");

    }

} /*End of display() */