- Forget about long paths unless you really need to care. You need to care if you're accepting a file path from another app, for example. You don't need to care if you're using your own files in your install directory; too much of Windows doesn't support long files (including explorer, as mentioned, not to mention third party apps), so it's very unlikely that you'll need to deal with them if you're just handling your own data.
- Work in utf-16 when dealing with file paths. Convert back and forth at the point of entry / exit to / from your app. It's unsurprising that you need to call the conversion function twice in order to find out how much memory to allocate, that's just how that works.
Don't change random registry settings or code pages on the user's computer, that's mad.
- Forget about long paths unless you really need to care. You need to care if you're accepting a file path from another app, for example. You don't need to care if you're using your own files in your install directory; too much of Windows doesn't support long files (including explorer, as mentioned, not to mention third party apps), so it's very unlikely that you'll need to deal with them if you're just handling your own data.
- Work in utf-16 when dealing with file paths. Convert back and forth at the point of entry / exit to / from your app. It's unsurprising that you need to call the conversion function twice in order to find out how much memory to allocate, that's just how that works.
Don't change random registry settings or code pages on the user's computer, that's mad.