Queue using linked list.

Queue.

•Define queue.
ANS.: Collection of elements using FIFO (First in First Out) mechanism.

•Operations performed on queue?
ANS.: enqueue (insertion), dequeue (deletion) & display.

•. Applications of queue?
ANS.: Round Robin technique for processor scheduling, Customer services application, Printer server routines.

•Types of queue?
ANS.: Linear queue, circular queue, double ended queue, priority queue.

Program for Queue using linked list.

Graphically Representation.

Source code. 

//queue using linked list
#include<stdio.h>
#include<stdlib.h>

struct node
{
	int data;
	struct node * addr;
};
struct node * head ,* rear;
void ins(int);
void del();
void disp();

int main()
{
	ins(10);\\ insert 10
	ins(20);\\ insert 10 20
	ins(30);\\ insert 10 20 30
        ins(40);\\ insert 10 20 30 40
	del();\\ delete 10(20 30 40) 
	del();\\ delete 20(30 40)
	del();\\ delete 30(40)
}

void ins(int val)
{
	struct node * temp,*i=head;
	temp=(struct node *) malloc (sizeof (struct node));
	temp -> data=val;
	temp-> addr=NULL;
	
	if(head==NULL)
	{
		head=temp;
		rear=temp;
	}
	else
	
		rear->addr=temp;
		rear=temp;
	disp();
}

  void disp()
  {
  	struct node * i=head;
  	
  		printf("\nqueue : ");
  		while(i!=NULL)
  		{
  			printf("%d  ",i->data);
  			i=i->addr;
		}
	
  }
  
  void del()
{
	//if queue is empty
	if(head==NULL)
		printf("Error:empty\n");
	//else
	else
	{	
	//more than one node exist
	head=head->addr;
	//only one node exist
	if(head==NULL)
		rear=NULL;
	}
	//display
	disp();
}

Output.

queue : 10
queue : 10  20
queue : 10  20  30
queue : 10  20  30  40
queue : 20  30  40
queue : 30  40
queue : 40