Dynamic arrays in a class

Expand Post »

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

(Toggle Plain Text)

#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

C++ Syntax (Toggle Plain Text)
#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++;
        }
    }
}
#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

(Toggle Plain Text)

#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

Similar Threads

Vector Base Class in C++
Delphi Class memory access violation. Why??? in Pascal and Delphi
binary file into class using dynamic arrays in C++
Dynamic Mmeory Allocation with 2D Arrays in C++
How to pass dynamic arrays? in C

chasee

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

4 posts
since Sep 2008

Permalink

Dec 9th, 2008

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:

C++ Syntax (Toggle Plain Text)
// 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];
}
// 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];
}

mahlerfive

Reputation Points: 33

Solved Threads: 18

Junior Poster in Training

Offline

77 posts
since Aug 2008

This thread is solved

Either the thread starter or a moderator has marked this thread as solved. You can most likely trust the responses and answers given. There is most likely no reason for any further responses to be posted here. If you have a related question, please start a new thread in this forum instead.

This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

Previous Thread in C++ Forum Timeline: opening user specified file

Next Thread in C++ Forum Timeline: Determining the number of unique words in a .txt file

DaniWeb Message

Cancel Changes

User Name
Password