What's the difference between void* and void**?

Question

It's the special property that void* can also be assigned a pointer to a pointer and cast back and the original value is received.

I read this line somewhere. Does it means void* and void** are same? What is the difference?

Edit

void* can hold any pointer. Then what's void** needed for?

Answer 1

One points at a black hole.

The other points at the thing pointing at the black hole.

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They're not really the same thing, but pointers can be converted to void *. You can convert int * to a void * because, well, it's a pointer. void ** is still a pointer (it just points to a pointer), and since it's a pointer, you can convert it to a void *. That make any sense?

That said, I don't think I've ever had a use for a void **, but if you needed an array of void *s, then the type would be void **. (In C) void * is often used to hold a pointer to some user data - but you won't know ahead of time what type that data will be. If you had an array of those, then void **.

Since you also have this tagged as C++: The previous case doesn't really apply: you could use a std::vector<void *>. Really, void * might be questionable - an abstract base might fit your purposes better. void * is useful mostly in C.