stack.cpp

#include<iostream>
#include<cstdlib>
#include<stdio.h>

using namespace std;




struct node                     /* declaration of a node*/
{
 int data;
 struct node *link;
};

struct node *start=NULL;       /* empty list: initialization*/
struct node *top, *temp;


void push(struct node *);
void pop();
void display();

int main(void)
{
 int opt;

 do                                    /* main menu*/
 {
  printf("\n     1.Push element into linked stack\n");
  printf("\n     2.Pop element from linked stack\n");
  printf("\n     3.Display stack contents\n");
  printf("\n     4.Quit\n");

  printf("\nEnter option:   ");
  scanf("%d",&opt);

  switch(opt)
  {
   case 1:
            top=(struct node *)calloc(1,sizeof(struct node));
            push(top);
            break;

   case 2:
            pop();
            break;

   case 3:
            display();
            break;

   case 4:
            exit(1);
  }
 } while(1);

}
                                               /* push operation*/
void push(struct node *t)
{
   int item;
   printf("\nEnter the element to be pushed  \n");
   scanf("  %d",&item);

   t->data=item;

   if(start==NULL)
       { t->link=0;
         start=t;
       }
   else
       {
         t->link=start;
         start=t;
       }
}

void pop()                                       /*pop operation*/
{
 if(start==NULL)
  printf("\nStack is empty! Pop impossible!\n");
 else
 {
  temp=start;
  start=start->link;
  free(temp);

 }
}

void display()                                  /*display stack */
{
 if(start == NULL)
  printf("\nStack is empty!\n");
 else
 {printf("contents of the stack:    \n");
  temp=start;
  while(temp->link !=0)
  {
   printf("\n  %d  ",temp->data);
   temp=temp->link;
  }
  printf("\n  %d  ",temp->data);
 }
}