Program for implement queue using dynamic implementation

                         /*         program........

wap to implement stack using dynamic implementation   */

#include<stdio.h>

#include<conio.h>

#include<alloc.h>

typedef struct node

{

      int data;

      struct node *next;

}node;

void main()

{

      int op,x;

      node *rear,*front,*p;

      front=NULL;

      rear=NULL;

      clrscr();

      do

      {

            printf("\nmain menu:");

            printf("\n1)insert\n2)delete\n3)display\n4)exit");

            printf("\nenter your choice");

            scanf("%d",&op);

            switch(op)

            {

                  case 1: printf("\nenter element");

                        if(rear==NULL)

                        {

                        rear=front=(node*)malloc(sizeof(node));

                        scanf("%d",&rear->data);

                        rear->next=NULL;

                        }

                        else

                        {

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

                        scanf("%d",&p->data);

                        p->next=NULL;

                        rear->next=p;

                        rear=p;

                        }

                        break;

                  case 2: p=front;

                        x=p->data;

                        front=p->next;

                        free(p);

                        printf("\ndeleted element is:%d",x);

                        break;

                  case 3: if(rear==NULL)

                        printf("\nqueue is empty");

                        else

                        {

                        p=front;

                        printf("\nqueue is:");

                        while(p!=NULL)

                        {

                              printf("<-%d",p->data);

                              p=p->next;

                        }

                        }

                        break;

            }

      }while(op!=4);

getch();

}