Void* C is a carrier for realizing polymorphism

Consider such a question , There is a machine composed of multiple functional blocks , And these plates are freely pluggable , And the parameters of each kind of plate management are also different . We use it C++ This kind of object-oriented language can easily realize such functions , Because object-oriented languages support polymorphism . So there is such a problem ：

C How language realizes polymorphism ？

Facing the above practical problems ,C++ This is how it works ：

class Board{
    
public:
	Board();
	virtual ~Board();
	virtual Board* getBoard() = 0;
	virtual void  setBoard(Board* board)=0;
private:
	int boardtype;
	Board* board;
}

class Board1 : public Board{
    
...
}
 It is this virtual function that realizes the dynamic management of the board .

C The language itself cannot realize such functions as virtual functions , But we still want to implement similar polymorphic functions ？

Null pointer （void *） Is the only tool we can use , Because a null pointer can point to any data type and can be forcibly converted to any type , Include malloc Such functions also return null pointers , So we use null pointers to solve the above practical problems ：

struct Slot
{
    
	int boardtype;
	void  *board;
};

struct Board1
{
    
	int prarm1;
	.
	.
	.
	int prarmn;
}

struct Board2
{
    
	int prarm1;
	.
	.
	.
	int prarmn;
}
...

// Card slot insert board 
struct Board2 *board = (struct Board2*)malloc(sizeof(struct Board2));
struct Slot slot;
slot.boardtype = 2;
slot.board = (void *)board;

Anyway, this realizes a C Polymorphism of language .