Im not recommending doing this, but you may want to allocate an address to use as a magic number. NULL is a magic number address that is guaranteed never to be

Im not recommending doing this, but you may want to allocate an address to use as a magic number. NULL is a magic number address that is guaranteed never to be a valid allocation. By allocating an address, you can creat your own magic number, that wont ever be used by any other allocation so you can give it special meaning in your code.