Queue

AIM:

            To implement queue in the list.

ALGORITHM:

Step 1: Start the program.

Step 2: Declare the necessary variables.

Step 3: Declare the structure node.

Step 4: Display the choices as

                  1. Addition

               2. Deletion

Step 5: Get the choice as input.

Step 6: If the choice is 1, then add the data into the queue.

Step 7: If the choice is 2, then pop the data entered first from the queue.

Step 8: Stop the program.

PROGRAM:

#include<iostream.h>

struct node

{

int data;

struct node*ptr;

};

typedef struct node queue;

queue *addnode(queue *);

queue *delnode(queue *);

queue *head=NULL;

queue *rear=NULL;

int k=1;

main()

{

int ch,k=1;

char d;

queue *q;

do

{

cout<<"\nQUEUE IMPLEMENTATION";

cout<<"\nThe Choices are:\n1.Addition\n2.Deletion\n";

cout<<"Enter a choice:";

cin>>ch;

switch(ch)

{

case 1:

if(k==1)

{

q=(queue*)malloc(sizeof(queue));

head=rear=q;

cout<<"Enter the data:";

cin>>q->data;

q->ptr=NULL;

k=0;

}

else if(k==0)

{

rear=addnode(rear);

}

break;

case 2:

if(k==1)

cout<<"Queue is empty";

else if(head->ptr==NULL)

{

k=1;

cout<<"The deleted data is "<<head->data;

head=NULL;

rear=NULL;

}

else

head=delnode(head);

break;

}

cout<<"\nDo you want to continue?:";

cin>>d;

}

while(d=='y'||d=='Y');

}

}

queue *addnode(queue *p)

{

queue *t;

t=new node;

cout<<"Enter the data:";

cin>>t->data;

p->ptr=t;

t->ptr=NULL;

return t;

}

queue *delnode(queue *b)

{

int c;

c=b->data;

cout<<"The deleted data is "<<c;

head=b->ptr;

return head;

}