linkqueu.c

generalised stack using array

/* TO PUSH AND POP AN ELEMENT INTO THE QUEUE USING LINK ALLOCATION */

#include<stdio.h>
#include<conio.h>

typedef struct link
{
	int e;
	struct link *next;
}queue;

queue *front,*rear,*temp;
void insert(queue *,int ele);
int delete(queue *);
void display(queue *);

void main()
{

	int ele,ch;
	char yn;
	queue s;
	front= rear = temp = NULL;
	do
	{
	clrscr();
	printf("\t\t ****** OPERATIONS ON A LINKED QUEUE ******\n\n");
	printf("1 . INSERTION\n");
	printf("2 . DELETION\n");
	printf("3 . EXIT\n");
	printf("\t Enter Your Choice... ");
	scanf("%d",&ch);
	switch(ch)
	{
		case 1 : printf("ENTER THE ELEMENT TO PUSH INTO THE QUEUE : ");
			 scanf("%d",&ele);
			 insert(&s,ele);
			 display(&s);
			 break;

		case 2 : ele = delete(&s);
			 display(&s);
			 break;

		case 3 : exit(0);
			 break;

		default : printf("\n\n\t OOPS WRONG CHOICE ENTERED!!!");
			  getch();
			  exit(0);
	}
	printf("\n\n DO YOU WANT TO PERFORM  MORE OPERATIONS ? (Y/N)");
	fflush(stdin);
	scanf("%c",&yn);
	}
	while(yn == 'y' || yn == 'Y');
}

void insert(queue *temp,int ele)
{
	temp = (queue*)malloc(sizeof (queue));
	if (temp == NULL)
	{
		puts("\n\n\t Memory Is Full!!!");
		return;
	}
	temp->e = ele;
	temp->next = NULL;
	if(rear == NULL)
		front=rear = temp;
	else
	{
		rear->next = temp;
		rear = temp;
	}
}

int delete(queue *temp)
{
	int ele;
	temp = (queue*)malloc(sizeof (queue));
	if (front == NULL)
	{
		puts("\n Memory is Empty,no element present!!!");
		return NULL;
	}
	temp = front;
	ele = temp->e;
	if(front==rear)
		front=rear=NULL;
	else
		front = front->next;
	free (temp);
	printf("\n The Deleted Element Is:%d",ele);
	return (ele);
}

void display(queue *temp)
{
	if(front != NULL)
	{
		temp = (queue*)malloc(sizeof(queue));
		temp = front;
		printf("\n\nCONTENTS OF THE QUEUE ARE : \n ");
		while(temp != NULL)
		{
			printf("\t%d\t",temp->e);
			temp = temp->next;
		}
	 }
}