C ++圆形结构

Question

Okay, so essentially I have a struct of a piece on a board, as follows:

struct piece
{
    int value;
    bool revealed;
    bool canMove(int x, int y)
    {
        //This is where the problem is.
        if (board[x][y].value == 13) //If it's not occupied
            return true;
        else
            return false;
    }
};

//Define the board
piece board[x][y];

And it's giving me errors such as 'board': undeclared identifier . How can I fix this? I've tried putting the board declaration before the struct, but then it just says that piece is an undeclared identifier.

I realize I could just pass in the board as a parameter, but I have several functions, and that would take a lot more time than I would like, so if there is any other solution, please tell me!

This question is related (but not identical) to Question

Answer 1

You have to decouple the class definition from the implementation of its member functions, so that the compiler always knows what you're talking about:

struct piece
{
    int value;
    bool revealed;
    bool canMove(int x, int y);  // this is sufficient for the moment
};

piece board[x][y];   // now, compiler knows what a piece is. 

bool piece::canMove(int x, int y) 
{                    // now board is known as well
    if (board[x][y].value == 13) 
        return true;
    else
        return false;
}

Answer 2

Declare canMove inside the class, then define it outside after you have declared board . At that point you can successfully refer to board .

Answer 3

You are mixing piece with pieces. This is really wrong design.

Your method canMove belongs to single piece. So its definition should rdflect this fact:

bool canMove() const
{
  return value == 13;
}

To get what you want to get from 2D array of pieces - just do:

board[x][y].canMove()

Of course you can creare new class Board to encapsulate its behaviour,like methods canMove with 2 arguments.