stack using dynamic memory allocation

 /*
    Author : PATEL DIVYAKUMAR BHARATBHAI
    Problem : Stack...using dynamic memory allocation...
    Date : 24/09/2022
*/
#include <stdio.h>
#include <stdlib.h>

// Global variable declaration ...which helps to not pass values through functions to avoid mistakes... //
int *stack;
int top = -1, n;

// Function declaration //
void push();
void pop();
void display();

void main()
{
    printf("Enter the number you want to make stack: ");
    scanf("%d", &n);

    stack = (int *)malloc(n * sizeof(n));

    printf("1. PUSH \n2. POP \n3. DISPlAY \n");

    while (1)
    {
        int ch;
        printf("Enter your choice: ");
        scanf("%d", &ch);

        switch (ch)
        {
            case 1:
                push();
                break;

            case 2:
                pop();
                break;

            case 3:
                display();
                break;

            default:
                free(stack);
                stack = NULL;
                printf("BYE... ");
                exit(0); // stdlib is needed to execute exit function... //
        }
    }
}

// Functions to execute stack code //

// PUSH function to push value in stack and change top reference... //
void push()
{
    if (top == n - 1)
    {
        printf("stack is FULL \n");
    }
    else
    {
        int num;
        printf("Enter the number you want to add: ");
        scanf("%d", &num);
        top++;
        stack[top] = num;
    }
}

// POP function to DELETE the last entered value... //
void pop()
{
    if (top == -1)
    {
        printf("Stack is EMPTY \n");
    }
    else
    {
        printf("Deleted value is %d \n", stack[top]);
        top--;
    }
}

// DISPLAY function to display stack values... //
void display()
{
    for (int i = 0; i <= top; i++)
    {
        printf("%d \n", stack[i]);
    }
}