If you just need a few simple values...
An ini-file could be used

More complex, there's XML and a variety of XML libraties (msxml being installed by default on any WinXP and up).

a database is an option, as well (embedded such as SQLite or external), but for just a simple savegame this seems overkill. I wouldn't consider a database solution unless you were tracking scores/games for dozens/hundres/thousands of players.

the disadvantage to the above is that they're all going to have portability issues.

You can roll your own as well of course, but then you need to do things the right way, and not make wrong assumptions as to how things work. C++ streams are not the most ideal solution for this sort of thing.