Library to merge two text files

I am writing C++ code generation utility (compiler) from XLS to bring design decisions right into the game code. Generated classes can be changed m开发者_StackOverflow社区anually after generation, so after following compilations generated files have to be merged with previous ones. What is the best way to merge them? Use some merging library or call external command?

Compiler written in C++, for Windows.

Thank you.

I would do the merging outside from the compiler by hand using some merge utility like svn merge (a commandline version exists here, perhaps you can automate this, but I wouldn't do this..), or BeyondCompare

Automatic merging can be very dangerous IMHO and think about what should the merger do automatically if there are conflicts?