actually, you can even store pointers to nothing in memory. you just do:

void x;
void* x_ptr = &x;

then you can use it to invoke functions that take no arguments like this:

void open_texteditor (void editor_choice)
{
    // do nothing with the editor_choice because there is only one sensible editor
    open_nano(); 
    return void;
}
void favorite_texteditor;
void result = open_texteditor(favorite_texteditor);
print_error_on_bad_result(result);

(note that this is a joke comment)

This has made a lot of people very angry and been widely regarded as a bad move.