A function to get the correct user config directory.

platform_dirs.cpp

#include <cstdlib>
#include <string>
#include <iostream>

#define PROJECT_NAME "OpenBoardView"

//using namespace std;;

// on linux use $XDG_CONFIG_HOME || $HOME/.config
// on windows use %APPDATA%
// on OSX use $HOME/Library/Preferences
std::string get_config_dir() {
  #ifdef __APPLE__
    if (const char *home = std::getenv("HOME")) {
      return std::string(home) + "/Library/Preferences/" PROJECT_NAME "/";
    }
  #elif defined _WIN32 || defined _WIN64
    if (const char *appdata = std::getenv("APPDATA")) {
      return std::string(appdata) + "\\" PROJECT_NAME "\\";
    }
  #else // Linux
    if (const char *xdg_conf = std::getenv("XDG_CONFIG_HOME")) {
      return std::string(xdg_conf) + "/" PROJECT_NAME "/";
    }
    if (const char *home = std::getenv("HOME")) {
      return std::string(home) + "/.config/" PROJECT_NAME "/";
    }
  #endif
  std::cerr << "Could not determin config directory!" << std::endl;
  exit (1);
}

// on linux use $XDG_CACHE_HOME || $HOME/.cache
// on windows use %LOCALAPPDATA% || %APPDATA%
// on OSX use $HOME/Library/Caches
std::string get_cache_dir() {
  #ifdef __APPLE__
    if (const char *home = std::getenv("HOME")) {
      return std::string(home) + "/Library/Caches/" PROJECT_NAME "/";
    }
  #elif defined _WIN32 || defined _WIN64
    if (const char *localAppdata = std::getenv("LOCALAPPDATA")) {
      return std::string(localAppdata) + "\\" PROJECT_NAME "\\";
    }
    if (const char *appdata = std::getenv("APPDATA")) {
      return std::string(appdata) + "\\" PROJECT_NAME "\\";
    }
  #else // Linux
    if (const char *xdg_cache = std::getenv("XDG_CACHE_HOME")) {
      return std::string(xdg_cache) + "\\" PROJECT_NAME "\\";
    }
    if (const char *home = std::getenv("HOME")) {
      return std::string(home) + "/.cache/" PROJECT_NAME "/";
    }
  #endif
  std::cerr << "Could not determin cache directory!" << std::endl;
  exit (1);
}

int main () {
  
  std::cout << "get_config_dir: \"" << get_config_dir() << "\"" << std::endl;
  
  return 0;
}