Question

how can I convert any object of my own class convert into pointer to void?

MyClass obj;
(void*)obj; // Fail

Answer 1

MyClass obj;
void *p;

p = (void*)&obj; // Explicit cast.
// or:
p = &obj; // Implicit cast, as every pointer is compatible with void *

But beware ! obj is allocated on the stack this way, as soon as you leave the function the pointer becomes invalid.

Edit: Updated to show that in this case an explicit cast is not necessary since every pointer is compatible with a void pointer.