linked_list_stack.c

/*Program of stack using linked list*/
#include<stdio.h>
#include<stdlib.h>
struct node
{
	int info;
	struct node *link;
} *top = NULL;
void push(int item);
int pop();
int peek();
int isEmpty();
void display();

int main()
{
	int choice,item;
	while(1)
	{
		printf("1.Push\n");
		printf("2.Pop\n");
		printf("3.Display item at the top\n");
		printf("4.Display all items of the stack\n");
		printf("5.Quit\n");
		printf("Enter your choice: ");
		scanf("%d",&choice);
		switch(choice)
		{
			case 1:
			printf("Enter the item to be pushed: ");
			scanf("%d",&item);
			push(item);
			break;
			
			case 2:
			item = pop();
			printf("Popped item is: %d\n",item);
			break;
			
			case 3:
			printf("Item at the top is %d\n",peek());
			
			case 4:
			display();
			break;
			
			case 5:
			exit(1);
			
			default:
			printf("Wrong choice\n");
		}/*End of switch*/
	}/*End of while*/
}/*End of main()*/

void push(int item)
{
	struct node *tmp;
	tmp = (struct node *)malloc(sizeof(struct node));
	if(tmp==NULL)
	{
		printf("Stack Overflow\n");
		return;
	}
	tmp->info = item;
	tmp->link = top;
	top = tmp;
}/*End of push()*/

int pop()
{
	struct node *tmp;
	int item;
	if(isEmpty())
	{
		printf("Stack Underflow\n");
		exit(1);
	}
	tmp = top;
	item = tmp->info;
	top = top->link;
	free(tmp);
	return item;
}/*End of pop()*/


int peek()
{
	if(isEmpty())
	{
		printf("Stack Underflow\n");
		exit(1);
	}
	return top->info;
}/*End of peek()*/

int isEmpty()
{
	if(top==NULL)
		return 1;
	else
		return 0;
}/*End of isEmpty()*/

void display()
{
	struct node *ptr;
	ptr = top;
	if(isEmpty())
	{
		printf("Stack is empty\n");
		return;
	}
	printf("Stack elements: \n");
	while(ptr!=NULL)
	{
		printf(" %d\n",ptr->info);
		ptr = ptr->link;
	}
	printf("\n");
}/*End of display()*/