linked stack

#include<stdio.h>
#include<stdlib.h>
void display();
void push();
void pop();
struct node
{
	int data;
	struct node *link;
};
int main()
{
	struct node *topptr = NULL;
	int choice,data;
	while(1)
	{
		printf("\n ENTER YOUR CHOICE: \n1.PUSH \n2.DISPLAY \n.3.POP \n.4.EXIT");
		scanf("%d",&choice);
		switch(choice)
		{
			case 1: 	printf("ENTER DATA:");
						scanf("%d",&data);
						push(&topptr,data);
						break;
			case 2:  display(&topptr);
						break;
			case 3:  pop(&topptr);
						break;
						
			case 4:  exit(0);
			
			default: printf("INVALID CHOICE");
						break;
		}
	}
}

void push(struct node **t, int data)
{
	struct node *newnode;
	newnode=(struct node *)malloc(sizeof(struct node));
	newnode-> data =data;
	newnode->link= *t;
	*t = newnode;
}

void display( struct node **t)
{
	struct node *temp;
	if(*t == NULL)
	{
		printf("empty");
	}
	else
	{
		temp= *t;
		while(temp ->link != NULL)
		{
			printf("%d", temp->data);
			temp = temp->data;
		}
	}
}

void pop(struct node **t)
{
	struct node *temp;
	if(*t=NULL)
	{
		printf("empty");
	}
	else
	{
		temp= *t;
		free(temp);
		*t = *t->link;
	}
}