Stack At lab - 15-10-17

#include<stdio.h>
#include<conio.h>
#include<stdbool.h>

#define SIZE 5

// int stack[SIZE] = {1,2,3,4,5,6,7,8,9,10};
int stack[SIZE-1];
int top = -1;


bool isEmpty()
{
    return stack[0] == NULL ? true : false;
}

bool isFull()
{
    return top == SIZE-1 ? true : false;
}

void push()
{
    int val;
    if(isFull() == false)
    {
        printf("Enter Value: ");
        scanf("%d", &val);
        stack[top+1] = val;
        top+=1;
    }
    else
    {
        printf("\n\n\nFull");
    }
}

void pop()
{
    if(!isEmpty()){
        stack[top] = NULL;
        top-=1;
    }
}

void peek()
{
    printf("\n Top peek element is %d\n", stack[top]);
}

void display()
{
    int i=0;
    printf("\n");
    for(i=0; stack[i] != NULL; i++)
    {
        printf(" %d -", stack[i]);
    }
    printf("\b\b\b\b\n");
}


int main()
{
    while(1)
    {
        int choice;
        printf("MENU \n 1. Push \n 2. Pop \n 3. Peak \n 4. Exit \n");

        scanf("%d", &choice);

        if(choice == 1)
        {
            push();
        }
        else if(choice == 2)
        {
            pop();

        }
        else if(choice == 3)
        {
            peek();
        }
        else if(choice == 4)
        {
            exit(1);
        }
        display();
    }
    return 0;
}