When to use a void pointer?

Question

I understand the use of void pointer for malloc implementation.

void* malloc  ( size_t size );

Can anyone suggest other reasons or provide

Answer 1

Next to interfacing with C, I find myself only using void pointers when I need to debug / trace some code and like to know the address of a certain pointer.

SomeClass * myInstance;
// ...
std::clog << std::hex << static_cast< void* >(myInstance) << std::endl;

Will print something like

0x42A8C410

And, in my opinion, nicely documents what I'm trying to do (know the pointer address, not anything about the instance)