Queue (code):

<br />#include<iostream>
#include<conio.h>
using namespace std;

struct queue
{
int data;
struct queue *link;
}*front,*rear,*temp,*ptr;

void insert()
{
int ele;
cout<<"Enter element to be inserted:"<<endl;
cin>>ele;
temp=new queue;
if(temp==NULL)
cout<<"Out of Memory !! Overflow !!!"<<endl;
else
{
temp->data=ele;
temp->link=NULL;
if(front==NULL)
{
front=rear=temp;
}
else
{
rear->link=temp;
rear=temp;
}
cout<<"Element has been inserted at end:"<<endl;
}
}

int Delete()
{
int info;
if(front==NULL)
{
cout<<"Underflow !!!"<<endl;
return 0;
}
else
{
temp=front;
info=front->data;
if(front==rear)
{
rear=NULL;
}
front=front->link;
temp->link=NULL;
delete temp;
cout<<info<<" deleted from queue:"<<endl;
}
}

void display()
{
if(front==NULL)
{
cout<<"Empty Queue !!!"<<endl;
}
else
{
ptr=front;
cout<<"front->";
while(ptr)
{
cout<<"[ "< data<<" ]->";
ptr=ptr->link;
}
cout<<"rear";
}
}

int main()
{
int opt,elem;
front=rear=NULL;
cout<<"\n ### Linked List Implementation of QUEUE Operations ### \n";
do
{
cout<<"\n Press 1-Insert, 2-Delete, 3-Display, 4-Exit\n";
cout<<"\n Your option ? ";
cin>>opt;
switch(opt)
{
case 1:
insert();
break;
case 2:
Delete();
break;
case 3: cout<<"Linked List Implementation of Queue: Status:\n";
display(); break;
case 4: cout<<"\n Terminating n"; break;
default: cout<<"\nInvalid Option !!! Try Again !! \n";
break;
}
cout<<"\n Press a Key to Continue . . . ";
getch();
}while(opt != 4);
getch();
return 0;
}

corollary :