Registry vs. INI file for storing user configurable application settings

Pros of config file:

1. Easy to do. Don't need to know any Windows API calls. You just need to know the file I/O interface of your programming language.
2. Portable. If you port your application to another OS, you don't need to change your settings format.
3. User-editable. The user can edit the config file outside of the program executing.

Pros of registry:

1. Secure. The user can't accidentally delete the config file or corrupt the data unless he/she knows about regedit. And then the user is just asking for trouble.
2. I'm no expert Windows programmer, but I'm sure that using the registry makes it easier to do other Windows-specific things (user-specific settings, network administration stuff like group policy, or whatever else).

If you just need a simple way to store config information, I would recommend a config file, using INI or XML as the format. I suggest using the registry only if there is something specific you want to get out of using the registry.

Jeff Atwood has a great article about Windows' registry and why is better to use .INI files instead.

My life would be a heck of a lot easier if per-application settings were stored in a place I could easily see them, manipulate them, and back them up. Like, say... in INI files.

• The registry is a single point of failure. That's why every single registry editing tip you'll ever find starts with a big fat screaming disclaimer about how you can break your computer with regedit.
• The registry is opaque and binary. As much as I dislike the angle bracket tax, at least XML config files are reasonably human-readable, and they allow as many comments as you see fit.
• The registry has to be in sync with the filesystem. Delete an application without "uninstalling" it and you're left with stale registry cruft. Or if an app has a poorly written uninstaller. The filesystem is no longer the statement of record-- it has to be kept in sync with the registry somehow. It's a total violation of the DRY principle.
• The registry is monolithic. Let's say you wanted to move an application to a different path on your machine, or even to a different machine altogether. Good luck extracting the relevant settings for that one particular application from the giant registry tarball. A given application typically has dozens of settings strewn all over the registry.

According to the documentation for GetPrivateProfileString, you should use the registry for storing initialisation information.

However, in so saying, if you still want to use .ini files, and use the standard profile APIs (GetPrivateProfileString, WritePrivateProfileString, and the like) for accessing them, they provide built-in ways to automatically provide "virtual .ini files" backed by the registry. Win-win!