Stack

#include<stdio.h>

#include<stdlib.h>

typedef struct data
{
    int a;
    struct data *next;
} data;
data *head=NULL;

void push(int x)
{
    data *first=(data*)malloc(sizeof(data));
    first->a=x;
    first->next=NULL;
    if(head==NULL)
    {
        head=first;
        return;
    }
    first->next=head;
    head=first;
    return;

}

int pop()
{

    if(head==NULL)
    {
        printf("Empty\n");
        return -1;
    }
    data *x=head->a;
    data *del=head;
    data *temp=head->next;
    head=temp;
    free(del);

    return printf("%d ",x);



}

int top()
{
    if(head==NULL)
    {
        printf("Empty\n");
        return -1;
    }
    return printf("%d ",head->a);
}

int main()
{
    /* push(6);
     push(5);
     push(4);
     pop();
     push(3);
     push(2);
     top();
     */
    while(1)
    {
        printf("Enter 1 for PUSH.\n");
        printf("Enter 2 for POP.\n");
        printf("Enter 3 for TOP.\n");
        printf("Enter 0 for Quit.\n");



        int m,n;
        scanf("%d",&m);
        if(m==1)
        {
            printf("Plz Enter:");
            scanf("%d",&n);
            push(n);
            printf("\n");
        }
        if(m==2)
        {

            pop();
             printf("\n");
        }
        if(m==3)
        {

            top();
             printf("\n");
        }
        if(m==0)
        {
            break;
        }


    }

}