Using globals in headerfiles

[Toyman]

Hey, I've just officially joined c++.com after lurking for the past few years.

I've been having trouble with globals in header files in my projects.

I have globals.h:

static int MIN_X = 1;
static int MAX_X = 100;
static int MIN_Y = 1;
static int MAX_Y = 100;

And I am trying to make a class in class.h:

class Board{
int board[MAX_X + 2][MAX_Y + 2];
};

But that throws an error:
"data member may not have variably modified type `int[(((unsigned int)(((int)MAX_X) + 1)) + 1u)][(((unsigned int)(((int)MAX_Y) + 1)) + 1u)]'|

How should I go about fixing it? I need MAX_X, MAX_Y in other files as well, and I want the Board class to be more dynamic in case I change it later.

Thanks

[kbw]

I've been having trouble with globals in header files

Don't define global variables in header files.

You seem to need constants rather than varaibles, so your code C++ ought to be:

const int MIN_X = 1;
const int MAX_X = 100;
const int MIN_Y = 1;
const int MAX_Y = 100;

or if you're using C:

#define MIN_X  1
#define MAX_X 100
#define MIN_Y 1
#define MAX_Y 100 

[Toyman]

Wow. Thanks
I usually do use const, but I swear I got errors from it so I used static.
It's working fine now :P

[1yR4jE8b]

If you want these variables available in other files why not make them static in the Board class? Doing it this way makes the code a bit clearer as well (imo), and you don't have to deal with the global variable issues.;

Board.h

class Board {
public:
  static const int MIN_X = 1, MAX_X = 2, MIN_Y = 1, MAX_Y = 100;
private:
  int board[MAX_X + 2][MAX_Y + 2];
};

main.cpp

#include <iostream>
#include "Board.h"

int main() {
  //ok I need MAX_X
  int x = Board::MAX_X;
  return 0;
}