Void pointer initialization? If not, what is it?

Question

I'm trying to understand a segment of code used as a parameter in C++ but I can't seem to find another example of it elsewhere on the internet. Here's the segment:

void (*cb)(void)

Is this another way of initializing a void pointer? What is the benefit of doing it like this versus void *cb?

Answer 1

In this example, cb is a pointer to a function which takes no arguments and has no return value

for example if I have

void printHello( ) {
    cout << "hello" << endl;
}

then I could later have

void (*cb)(void);
cb = printHello;

I can call the function using:

cb(); 

which will call printHello();

The utility of this is that I can now assign different functions to cb and call them and pass them around to other functions like any other pointer variable.

Often for clarity, programmers will create a specific type for this to avoid having to write this mouthful:

typedef void (*tPrtToVoidFn)(void);
tPtrToVoidFn  cb;
cb = printHello;

For comparison, a pointer to a function that returns an int would look like:

int (*ptrToFunctionReturningInt)(void);

and a pointer to a function taking an int and returning nothing would look like:

void (*ptrToFunctionReturningNothing)(int);