Size of array (new[])

Question

In debug heap I can get size of array, which was created by new[]:

int size = *((int *)((char *)ptr - 16));

It is working correctl

Answer 1

Any way that involves mining something from the CRT is undefined and cannot work 100%.
Your only way is to override operator new[] that will store the size somewhere defined, like allocating bigger object with size prefix.