Applications of the queue are given as follows:

• Queues are widely used as waiting lists for a single shared resource like a printer, disk, or CPU.
• Queues are used in the asynchronous transfer of data (where data is not being transferred at the same rate between two processes) for eg. pipes, file IO, and sockets.
• Queues are used as buffers in most applications like MP3 media players, CD players, etc.
• Queues are used to maintain the playlist in media players to add and remove the songs from the playlist.
• Queues are used in operating systems for handling interrupts.

1. #include<stdio.h>
2. #include<stdlib.h>
3. void beg_insert(int);
4. struct node
5. {
6.     int data;
7.     struct node *next;
8. };
9. struct node *head;
10. void main ()
11. {
12.     int choice,item;
13.     do
14.     {
15.         printf(“nEnter the item which you want to insert?n”);
16.         scanf(“%d”,&item);
17.         beg_insert(item);
18.         printf(“nPress 0 to insert more ?n”);
19.         scanf(“%d”,&choice);
20.     }while(choice == 0);
21. }
22. void beg_insert(int item)
23. {
25.     struct node *ptr = (struct node *)malloc(sizeof(struct node));
26.     struct node *temp;
27.     if(ptr == NULL)
28.     {
29.         printf(“nOVERFLOW”);
30.     }
31.     else
32.     {
33.         ptr -> data = item;
34.         if(head == NULL)
35.         {
36.             head = ptr;
37.             ptr -> next = head;
38.         }
39.         else
40.         {
41.             temp = head;
42.             while(temp->next != head)
43.                 temp = temp->next;
44.             ptr->next = head;
45.             temp -> next = ptr;
46.             head = ptr;
47.         }
48.     printf(“nNode Insertedn”);
49.     }
51. }

Push:

• Increment the variable top so that it can refer to the next memory allocation
• Copy the item to at the array index value equal to the top
• Repeat steps 1 and 2 until the stack overflows

Pop:

• Store the topmost element into the another variable
• Decrement the value of the top
• Return the topmost element

Row-Major Order: If the array is declared as a[m][n] where m is the number of rows while n is the number of columns, then the address of an element a[i][j] of the array stored in row-major order is calculated as,

Address(a[i][j]) = B. A. + (i * n + j) * size

Column-Major Order: If the array is declared as a[m][n] where m is the number of rows while n is the number of columns, then the address of an element a[i][j] of the array stored in column-major order is calculated as

Address(a[i][j]) = ((j*m)+i)*Size + BA.