Question

I’m in the process of trying to make a game-in-progress more modular. I’d like to be able to declare a single array of all the room_t objects in the game (room_t rooms[]), store it in world.cpp and call it from other files.

The truncated code below does not work, but it’s as far as I’ve gotten. I think I need to use extern but have not been able to find a method that works correctly. If I try and declare the array in the header file, I get a duplicate object error (as each file calls world.h, I’d assume).

main.cpp

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

int main()
{
    int currentLocation = 0;
    cout << "Room: " << rooms[currentLocation].name << "\n";
    // error: 'rooms' was not declared in this scope
    cout << rooms[currentLocation].desc << "\n";    
    return 0;
}

world.h

#ifndef WORLD_H
#define WORLD_H
#include <string>


const int ROOM_EXIT_LIST = 10;
const int ROOM_INVENTORY_SIZE = 10;

struct room_t
{
    std::string name;
    std::string desc;
    int exits[ROOM_EXIT_LIST];
    int inventory[ROOM_INVENTORY_SIZE];
};  

#endif

world.cpp

#include "world.h"

room_t rooms[] = {
  {"Bedroom", "There is a bed in here.", {-1,1,2,-1} },
  {"Kitchen", "Knives! Knives everywhere!", {0,-1,3,-1} },
  {"Hallway North", "A long corridor.",{-1,-1,-1,0} },
  {"Hallway South", "A long corridor.",{-1,-1,-1,1} }
};

Answer 1

Just add extern room_t rooms[]; in your world.h file.