Dynamic arrays in a class
 

I'm working on a program that has a class Board, and two inherited classes that will implement different games, but I'm having problems with setting up the initial Board class. The problem is that I don't know how to make it so the board array in the protected section of the Board.h file takes on the values input in a and b in the main.cpp file.

Here's my main.cpp

#include <iostream>

#include "Board.h"



using namespace std;



int main()

{

    Board Game;

    int a, b;

    cout << "enter a: ";

    cin >> a;

    cout << endl << "enter b: ";

    cin >> b;

    cout << endl;

    Game.set_board(a,b);

    Game.display();



    return 0;

}

my Board.cpp

#include "Board.h"

#include <iostream>



using namespace std;



Board::Board()

{



}



void Board::display()

{

    for (int i = 0; i < width; i++)

    {

        for (int j = 0; j < height; j++)

        {

            cout << board[i][j] << " ";

        }

        cout << endl;

    }

}



void Board::set_board(int a, int b)

{

    width = a;

    height = b;



    int num = 1;



    for (int i = 0; i < width; i++)

    {

        for (int j = 0; j < height; j++)

        {

            board[i][j] = num++;

        }

    }

}

and my Board.h file

#ifndef BOARD_H_INCLUDED

#define BOARD_H_INCLUDED



class Board

{

    public:

    Board();

    void display();

    void set_board(int, int);



    protected:

    int height, width;

    int board[4][4];

};



#endif // BOARD_H_INCLUDED

Re: Dynamic arrays in a class
 

Instead of: int board[4][4];
Replace with: int** board;
Now we can dynamically allocate space for the 2D board array.

In set_board(), we need to do the dynamic allocation like so:

// First allocate for the first dimension

board = new int*[height];



// Now allocate for the second dimension

for( int i = 0; i < height; i++ ) {

   board[i] = new int[width];

}