Queue in Data Structure Using Cpp

What is Queue ?

Queue is an abstract data structure, somewhat similar to Stacks.Unlike stacks, a queue is open at both its ends.

Sequence of Elements : FIFO First Come First Out

Pointers : 2 Pointers

Implementation of Queue Program

/*
Implementation of Queue:

*/

#include<iostream.h>
#include<stdlib.h>
#include<conio.h>
#define size 5

struct queue
{
int queue_box[size];
int front,rear;
}Queue_call;

int queueFull()
{
if(Queue_call.rear>=size-1)
return 1;
else
return 0;
}

int queueEmpty()
{
if((Queue_call.front==-1)||(Queue_call.front>Queue_call.rear))
return 1;
else
return 0;
}

int insert_item(int item)
{
if(Queue_call.front==-1)
Queue_call.front++;
Queue_call.queue_box[++Queue_call.rear]=item;
return Queue_call.rear;
}

int delete_item()
{
int item;
item=Queue_call.queue_box[Queue_call.front];
Queue_call.front++;
cout<<"\nThe delete_item item is "<<item;
return Queue_call.front;
}

void display()
{
int i;
for(i=Queue_call.front;i<=Queue_call.rear;i++)
cout<<" "<<Queue_call.queue_box[i];
}

void main()
{
int ch,item;

clrscr();
Queue_call.front=-1;
Queue_call.rear=-1;

cout<<"\n Queue Implementation";
do
{
cout<<"\n---------------\n Main Menu";
cout<<"\n1:Insert \n2:Delete \n3:Display \n4:Clear \n5:Exit";
cout<<"\nSelect Operation:";
cin>>ch;

switch(ch)
{
case 1:
if(queueFull())
{
cout<<"Cannot insert the element";
}
else
{
cout<<"Enter the number to be inserted:";
cin>>item;
insert_item(item);
}
break;

case 2:
if(queueEmpty())
{
cout<<"\nQueue is Empty";
}
else
{
delete_item();
}
break;

case 3:
if(queueEmpty())
{cout<<"\nQueue Is Empty";}
else
{display();}
break;
case 4: clrscr(); break;
case 5:
cout<<"\nEnd of Program...";
}
}while(ch!=5);
getch();
}

Output