在gameBoard中实现以下功能的代码

Question

gameBoard *InitBoard(char *space, int nos,void (*toStringGameboard)(void *S), int (* getNumberOfSpaces) (void * S),char * (* getTypeOfSpace)(void * S))
    {
        gameBoard *gb= (gameBoard *) malloc(sizeof(gameBoard));
        strcpy(gb->typeOfSpace, space);
        //implement the function pointers
        return gb;
    }

    char * getTypeOfSpace(void  *board) {
        return ???;
    }
    
    int getNumberOfSpaces(void * board) {
        return ???;
    }

    void toStringGameboard(void * S){
    //print out something informative and cute
        return;
    }

我对 void 指针很困惑。到目前为止，对于第一种方法，这就是我所拥有的。 本质上，因为我不明白发生了什么， 我刚刚重复了函数的参数以尝试初始化它们。 这是正确的，如果不是，我从这里去哪里？

gameBoard *InitBoard(char *space, int nos,void (*toStringGameboard)(void *S), 
          int (* getNumberOfSpaces) (void * S),char * (* getTypeOfSpace)(void * S))
{
    gameBoard *gb= (gameBoard *) malloc(sizeof(gameBoard));
    strcpy(gb->typeOfSpace, space);
    void(*toStringGameboard)(void *S);
    int(*NumberOfSpaces)(void *S);
    char(*getTypeOfSpace)(void *S);
    return gb;
}

对于第二种方法，我想我可以使用写在 gameBoard.h 中的 char typeOfSpace[20]，但我不完全确定如何去做：

typedef struct gameBoard {
    char typeOfSpace[20];   //"WIN", "BACK", "FORWARD", "SAFE"
    int numberOfSpaces; //if the type of space is "BACK", "FORWARD", then this is the number of spaces to move
        int (* getNumberOfSpaces) (void * S);
    void (* toStringGameboard)(void * S);
    char * (* getTypeOfSpace)(void * S);
}gameBoard;

gameBoard *InitBoard(char *typeOfSpace, int nos,
                    void (*toStringGameboard)(void *S), 
                    int (* getNumberOfSpaces) (void * S),
                    char * (* getTypeOfSpace)(void * S));

char * getTypeOfSpace(void  *board);
int getNumberOfSpaces(void *board);
void toStringGameboard(void *board);

不知道如何做后两个，任何帮助都会很棒！

Answer 1

在InitBoard 中，您显然应该初始化gb 的字段。

gameBoard *InitBoard(
   char *space,
   int nos,
   void (*toStringGameboard)(void *S),
   int (*getNumberOfSpaces) (void *S),
   char *(*getTypeOfSpace)(void *S)
) {
   gameBoard *gb = malloc(sizeof(gameBoard));
   strcpy(gb->typeOfSpace, space);
   gb->numberOfSpaces    = ???;
   gb->getNumberOfSpaces = ???;
   gb->toStringGameboard = ???;
   gb->getTypeOfSpace    = ???;
   return gb;
}

原来所有必要的值都作为参数提供。

gameBoard *InitBoard(
   char *space,
   int nos,
   void (*toStringGameboard)(void *S),
   int (*getNumberOfSpaces) (void *S),
   char *(*getTypeOfSpace)(void *S)
) {
   gameBoard *gb = malloc(sizeof(gameBoard));
   strcpy(gb->typeOfSpace, space);
   gb->numberOfSpaces    = nos;
   gb->getNumberOfSpaces = getNumberOfSpaces;
   gb->toStringGameboard = toStringGameboard;
   gb->getTypeOfSpace    = getTypeOfSpace;
   return gb;
}

---

调用getTypeOfSpace（等）的意图肯定如下：

gb->getTypeOfSpace(gb)

因此，其他人的board 参数实际上将是gameBoard*。

char *getTypeOfSpace(void *board) {
   gameBoard *gb = board;
   return ???;
}