How to grow a pointer or an array in C at runtime (without knowing the end length at compile time)

Question

I want to grow an array at runtime (without predining the length with a macos)

I have the following questions

1. is it possible to do it with an array?
2. If not shall I use a pointer to int?

I tried the following code (and expecting 012 as output) but get 000

#include <stdlib.h>
#include <stdio.h>

int main()
{
    int *arr = NULL; 
    size_t n = 0; 
    for (int i = 0; i < 3; ++i) { 
        arr = realloc(arr, (n + 1) * sizeof *arr); 
        arr[n++] = i; 
        printf("%d", *arr);
    } 
}

Answer 1

OP's mostly has it.

It is just printing the first element each time.

    // printf("%d", *arr);
    printf("%d", arr[n-1]);

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is it possible to do it with an array?

No. In C an array cannot change size once it is defined.

The memory size allocated and referenced by a pointer can change though.