Saving Config Changes
How could we extend the Config class to allow writing the configuration back to a file, effectively saving changes made in-game?
To enable saving the configuration back to a file, we need to add a Save() method to our Config class.
This method will do the reverse of Load(): it will take the current values of the Config object's members and write them to a file in the correct format.
Implementing Save()
Here's how we can implement the Save() method:
#include <SDL.h>
#include <iostream>
#include <string>
#include <vector>
class Config {
public:
std::string WindowTitle;
int WindowWidth;
int WindowHeight;
std::vector<int> Levels;
void Save(const std::string& Path) {
SDL_RWops* File{SDL_RWFromFile(
Path.c_str(), "w")};
if (!File) {
std::cout << "Failed to open config file "
"for writing: " << SDL_GetError() << "\n";
return;
}
std::string Content{""};
Content += "WINDOW_TITLE: "
+ WindowTitle + "\n";
Content += "WINDOW_WIDTH: "
+ std::to_string(WindowWidth) + "\n";
Content += "WINDOW_HEIGHT: "
+ std::to_string(WindowHeight) + "\n";
Content += "LEVELS: ";
for (size_t i{0}; i < Levels.size(); ++i) {
Content += std::to_string(Levels[i]);
if (i < Levels.size() - 1) {
Content += ",";
}
}
Content += "\n";
SDL_RWwrite(
File,
Content.c_str(),
Content.size(),
1
);
SDL_RWclose(File);
}
};
int main() {
Config MyConfig;
MyConfig.WindowTitle = "My Awesome Game";
MyConfig.WindowWidth = 1024;
MyConfig.WindowHeight = 768;
MyConfig.Levels = {1, 2, 3, 4, 5};
MyConfig.Save("config.txt");
}WINDOW_TITLE: My Awesome Game
WINDOW_WIDTH: 1024
WINDOW_HEIGHT: 768
LEVELS: 1,2,3,4,5Explanation
SDL_RWFromFile()for Writing: We useSDL_RWFromFile()with the "w" mode to open the file for writing. If the file doesn't exist, it will be created. If it does exist, it will be overwritten.- Building the
ContentString: We create astd::stringcalledContentand build it up line by line, using+to append each key-value pair. We usestd::to_string()to convert numeric values to strings. SDL_RWwrite(): We useSDL_RWwrite()to write the entire Content string to the file.SDL_RWclose(): We close the file usingSDL_RWclose().
Usage Example
In your game, you might modify the Config object's properties during gameplay (e.g., the player changes settings in a menu).
Then, you can call Save("config.txt") to save the updated configuration to the file, making the changes persistent across game sessions.
Parsing Data using std::string
Learn how to read, parse, and use config files in your game using std::string and SDL_RWops