Thread: Build error

Multiple definitions of "board". Here are my files.
main.cpp

Code:

#include <stdlib.h>
#include "global_functions.h"

int main(int argc, char** argv) {
    initialize_game();
    return (EXIT_SUCCESS);
}

global_functions.cpp

Code:

#include "global_functions.h"
#include <iostream>
#include <stdio.h>
void initialize_game(){
    //set the board up in the initial configuration
    
    std::cout << "Who goes first?" << std::endl;
    std::cout << "P for player" << std::endl;
    std::cout << "C for computer" << std::endl;

    char response;
    std::cin.get(response);}

Code:

#ifndef _GLOBAL_FUNCTIONS_H
#define	_GLOBAL_FUNCTIONS_H
enum{A, B, C, D, E, COLUMNS};
enum{PROOK, PPAWN, PKNIGHT, PBISHOP, CBISHOP, CKNIGHT, CPAWN, CROOK, ROWS};

int board[ROWS][COLUMNS]= {{0,1,1,1,0},
                          {1,1,1,1,1},
                          {0,0,1,0,0},
                          {0,0,0,0,0},
                          {0,0,0,0,0},
                          {0,0,2,0,0},
                          {2,2,2,2,2},
                          {0,2,2,2,0}};
void initialize_game();
#endif	/* _GLOBAL_FUNCTIONS_H */

I don't see how the board is being defined multiple times. The file is getting included twice but the inclusion guards should take care of that. Can anybody see what I did wrong?

Code:

int board[ROWS][COLUMNS]= {{0,1,1,1,0},
                          {1,1,1,1,1},
                          {0,0,1,0,0},
                          {0,0,0,0,0},
                          {0,0,0,0,0},
                          {0,0,2,0,0},
                          {2,2,2,2,2},
                          {0,2,2,2,0}};

You are initializing this in an include file which is included into multiple files. You should move this to one of the cpp files and then in this header have:

[code]
extern int board[ROWS][COLUMNS];

Jim

Originally Posted by jimblumberg

Code:

int board[ROWS][COLUMNS]= {{0,1,1,1,0},
                          {1,1,1,1,1},
                          {0,0,1,0,0},
                          {0,0,0,0,0},
                          {0,0,0,0,0},
                          {0,0,2,0,0},
                          {2,2,2,2,2},
                          {0,2,2,2,0}};

You are initializing this in an include file which is included into multiple files. You should move this to one of the cpp files and then in this header have:

[code]
extern int board[ROWS][COLUMNS];

Jim

Hmm I see, thanks. I thought the #ifndef directive would have kept it from being defined more than once for the whole program. So things defined with #define are only visible to the file they are in and files that include them, but the "board" variable I declared was global to the whole program? So when I included the file twice it actually processed my header file twice...Is that how it is working?

What it is doing is trying to create 2 variables both named "board" in the global scope. The header file is processed by every file that "includes" it. See this link Basics-of-C-plus-plus-Include-Files for a better explanation.

JIm

Thank you.