Question

I’ve already searched something abou this but I’ve still don’t understand it..

file1.h

extern int *game_array[5];

Player.c

 #include "file1.h"

   void *delete_player(player_struct *player)
   {
     ... //some code

     game_array[5] = 5;  //undefined reference to `game_array`

     ... //some code
   }

When I don’t use extern it “work’s fine” = I can build it withou errors, but the program’s not finished ..
I suppose the using extern is fine but something is wrong ..
I want to use this game_array … array of games on server from all my .c source files, there’s only one instance of this array in my aplication.

Answer 1

You need to define game_array in one of your .c files, and compile/link that file into your executable.

The definition will look like this:

int *game_array[5];

What your file1.h is saying is basically “There exists a variable called game_array somewhere in my project, and it has such-and-such type”. However, the variable doesn’t actually exist until you’ve defined it somewhere (typically, in a .c file).