Question

I’m writing a simple program using SDL, but I’m running into a strange problem. First the code:

#ifndef GLOBAL_VARIABLES_H
#define GLOBAL_VARIABLES_H

#include <string>
#include <cassert>
#include "SDL.h"
#include "SDL_image.h"
using std::string;

const int SCREEN_WIDTH = 800;
const int SCREEN_HEIGHT = 600;
const int SCREEN_BPP = 32;

const string MAIN_BACKGROUND_FILENAME = "tempBackground.jpg";



SDL_Rect CARD_CLIPS[2];

const int CARD_BACK = 0;
const int CARD_FRONT = 1;

CARD_CLIPS[CARD_BACK].h = 196;
CARD_CLIPS[CARD_BACK].w = 286/2;
CARD_CLIPS[CARD_BACK].x = 286/2;
CARD_CLIPS[CARD_BACK].y = 0;

CARD_CLIPS[CARD_FRONT].h = 196;
CARD_CLIPS[CARD_FRONT].w = 286/2;
CARD_CLIPS[CARD_FRONT].x = 0;
CARD_CLIPS[CARD_FRONT].y = 0;

#endif

The error I’m getting is this:

1>c:\users\--\global variables.h(23): error C2466: cannot allocate an array of constant size 0

1>c:\users\--\global variables.h(23): error C2143: syntax error : missing ';' before '.'

1>c:\users\--\global variables.h(23): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

1>c:\users\--\global variables.h(23): error C2371: 'CARD_CLIPS' : redefinition; different basic types

1>c:\users\--\global variables.h(18) : see declaration of 'CARD_CLIPS'

Repeat same error for each time I try to initialize an element of the SDL_Rect.

Note that the SDL part has nothing to do with the problem. If I try to declare an int array and initialize it in the same way, I get the exact same error. If I put any of this in my main.cpp it works completely fine.

Thanks for the help. Let me know if additional information is needed.

EDIT: Note that I get no errors except for when I try and use arrays in the header file. Though I do what to understand the conventional way to do things, I also want to understand why, from a fundamental standpoint, I can’t declare and initialize arrays in a header file like this.

Answer 1

First, variable definitions shouldn’t be in header files, only extern declarations.

Second, you can initialize variables (including arrays) in the definition, or assign the content as executable statements inside a function. You can’t put executable statements at file scope.

---

Array initialization looks like this:

int a[4] = { 1, 4, 9, 16 };

not like this:

int a[4];
a[0] = 1;  // ILLEGAL outside a function!
a[1] = 4;
a[2] = 9;
a[3] = 16;