B-Q2.c

#include <stdio.h>
#include <stdlib.h>

struct node
{
    int info;
    struct node *ptr;
}*top,*top1,*temp;

void push(int data);
void pop(); 
void display();
void create();
 
void main()
{
    int data, choice;
    create();
 
    while (1)
    {
        printf("\n\n 1 - Push");
        printf("\n 2 - Pop");
        printf("\n 3 - Dipslay"); 
        printf("\n Enter choice : ");
        scanf("%d", &choice);
 
        switch (choice)
        {
        case 1:
            printf(" Enter data : ");
            scanf("%d", &data);
            push(data);
            break;
        case 2:
            pop();
            break; 
        case 3:
            display();
            break;
        default :
            printf(" Wrong input, please choose 1, 2 or 3.");
            break;
        }
    }
}

void create()
{
    top = NULL;
}

void push(int data)
{
    if (top == NULL)
    {
        top =(struct node *)malloc(1*sizeof(struct node));
        top->ptr = NULL;
        top->info = data;
    }
    else
    {
        temp =(struct node *)malloc(1*sizeof(struct node));
        temp->ptr = top;
        temp->info = data;
        top = temp;
    } 
}

void display()
{
    top1 = top;
 
    if (top1 == NULL)
    {
        printf("Empty");
        return;
    }
 
    while (top1 != NULL)
    {
        printf("%d ", top1->info);
        top1 = top1->ptr;
    }
 }

void pop()
{
    top1 = top;
 
    if (top1 == NULL)
    {
        printf("\n Error : Stack already empty, can't pop.");
        return;
    }
    else
        top1 = top1->ptr;
    printf("\n Popped value : %d", top->info);
    free(top);
    top = top1; 
}