Queue

#include<iostream.h>

#include<conio.h>

#include<malloc.h>

struct node

{

int data;

struct node *link;

};

int main()

{

clrscr();

struct node *newnode,*ptr,*pptr,*start=NULL;

int ch,count=0,pos;

start=NULL;

while(1)

{

//view of queue

clrscr();

count=0;

ptr=start;

while(ptr!=NULL)

{

cout<<"\n["<<ptr->data<<"]";

ptr=ptr->link;

count++;

}

cout<<"\n\nTotal "<<count<<" nodes\n\n";

cout<<"\n MENU\n______\n\n";

cout<<"1. Push\n2. Pop\n0. EXIT\n\nchoice: ";

cin>>ch;

switch(ch)

{

case 1:

newnode=(node*)malloc(sizeof(node));

if(newnode==NULL)

{

cout<<"\nout of memory\n\npress any key to continue..";

getch();

break;

}

cout<<"\n\nEnter the data:\n";

cin>>newnode->data;

if(start==NULL)

{

start=newnode;

start->link=NULL;

break;

}

newnode->link=start;

start=newnode;

break;

case 2:

if(start==NULL)

{

cout<<"\nUnderflow\n\nPress any key to  continue..";

getch();

break;

}

pptr=NULL;

ptr=start;

while(ptr->link!=NULL)

{

pptr=ptr;

ptr=ptr->link;

}

if(pptr==NULL)

{

start=NULL;

}

pptr->link=NULL;

free(ptr);

break;

case 0://exit

//freeing all the memory before exit

while(start!=NULL)

{

ptr=start;

start=start->link;

free(ptr);

}

return 0;

}//end of switch

}//end of while

}//end  of main