Stack Implementation (without graphical display)

/* Stack Implementation (without graphical display) */

#include<stdio.h>
#include<conio.h>
#define SIZE_OF_STACK 5

struct stack
{
 int TOP;
 int slot[SIZE_OF_STACK];
};

void push(s,item)
struct stack *s;
int item;
{
	if(s->TOP==SIZE_OF_STACK-1)
	{
		printf("\nERROR : Stack Overflow !");
	}
	else
	{
		(s->TOP)++;
		s->slot[s->TOP]=item;
		printf("\nPush Operation Successful");
	}
}

void pop(s)
struct stack *s;
{
	if(s->TOP==-1)
	{
		printf("\nERROR : Stack Underflow !");
	}
	else
	{
		printf("%d",s->slot[s->TOP]);
		(s->TOP)--;
	}
}

void peep(s,slot_number)
struct stack s;
int slot_number;
{
	slot_number--;
	if(slot_number<0)
	{
		printf("\nERROR : Invalid Slot Number !");
	}
	else if(slot_number<SIZE_OF_STACK&&slot_number>s.TOP)
	{
		printf("\nERROR : Item does not exist. Topmost element is at %d !",s.TOP+1);
	}
	else if(slot_number>SIZE_OF_STACK-1)
	{
		printf("\nERROR : Slot Number beyond bounds of Stack. Stack Size is %d !",SIZE_OF_STACK);
	}
	else
	{
		printf("%d",s.slot[slot_number]);
	}
}

void main()
{
 struct stack s1;
 int choice,item,slot_number;
 s1.TOP=-1;
 clrscr();
 while(choice!=5)
 {
  clrscr();
  item=0;
  printf("\n ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ»");
  printf("\n º          MAIN MENU           º");
  printf("\n ÌÍÍÍÍÍËÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ͹");
  printf("\n º     º                        º");
  printf("\n º  1  º  Push                  º");
  printf("\n º  2  º  Pop                   º");
  printf("\n º  3  º  Peep                  º");
  printf("\n º  4  º  Display all elements  º");
  printf("\n º  5  º  Exit                  º");
  printf("\n º     º                        º");
  printf("\n ÈÍÍÍÍÍÊÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍͼ");
  printf("\nEnter your choice : ");
  scanf("%d",&choice);

	  switch(choice)
	  {
		case 1:
			printf("\nEnter Item to be pushed : ");
			scanf("%d",&item);
			push(&s1,item);
			break;
		case 2:
			if(s1.TOP!=-1)
			{
				printf("\nPopped Value is ");
			}
			pop(&s1);
			break;
		case 3:
			printf("\nEnter Slot Number : ");
			scanf("%d",&slot_number);
			if(slot_number>0&&slot_number<=s1.TOP+1)
			{
				printf("\nPeeped value is ");
			}
			peep(s1,slot_number);
			break;
		case 4:
			for(slot_number=1,printf("\n");slot_number<=s1.TOP+1;slot_number++)
			{
				 printf(" ");
				 peep(s1,slot_number);
			}
			break;
		case 5:
			printf("\nBye Bye !");
			break;
		default:
			printf("\nEnter a valid choice number (1-5) !");
	  }
	  getch();
 }

}