stack LL implementation.c

//Language:- C
#include<stdio.h>
#include<stdlib.h>

typedef struct node
{
    int data;
    struct node *next;
}node;

int count=-1;  //to count elements in stack

void main()
{
    int choice, data, reply;
    node *top;

    top=NULL;  //Empty Stack created

    do
    {
        printf("\n1. Push an element onto stack.\n");
        printf("2. Pop an element from stack.\n");
        printf("3. Display current stack contents.\n");
        printf("4. Exit.\n");
        printf("\nEnter your choice:- ");
        scanf("%d", &choice);
        switch(choice)
        {
        case 1:
            {
                printf("\nEnter an integer element:- ");
                scanf("%d", &data);
                reply=push(data, &top);
                if(reply==1)
                    printf("\nValue Pushed.\n");
                else
                    printf("\nMemory Allocation Failed.\n");
                break;
            }
        case 2:
            {
                reply=pop(&top);
                if(reply==0)
                    printf("\nStack Underflows.\n");
                else
                    printf("\nPopped Value is %d.\n", reply);
                break;
            }
        case 3:
            {
                if(top==NULL)
                {
                    printf("\nThe stack is empty\n");
                    break;
                }
                else
                {
                    display(top);
                    break;
                }
            }
        case 4:
                exit(0);
        default:
            {
                printf("\nInvalid Input. Try Again.\n");
                break;
            }
        }

    }while(1);
}

int push(int data, node **top)
{
    node *temp;
    temp=(node*)malloc(sizeof(node));  //to create a new room in stack

    if(!temp)
        return 0;  //memory allocation failed

    temp->data=data;  //pushing given data
    temp->next=*top;

    *top=temp;  //storing the address of the latest element in top
    count++;
    return 1;  //value pushed
}

int pop(node **top)
{
    node *temp;
    int data;

    if(*top==NULL)
        return 0;  //stack underflows
    else
    {
        temp=*top;
        *top=(*top)->next;
        data=temp->data;  //to show the popped value

        free(temp);  //deleting the node
        count--;
        return data;
    }
}

void display(node *element)
{
    int i=count;
    while(element!=NULL)
    {
        printf("Element %d - %d\n", i--, element->data);
        element=element->next;
    }
}