How should I combine two paths including backwards relative paths?

I have an absolute path, and a relative path, and I want to combine the two, is there any built-in way?

The relative path can be as well "../../aa2/file.exe".

(path.combine does not support it - which is pretty bizarre 开发者_JAVA技巧by itself.)

Try Path.GetFullPath(Path.Combine(abs, rel))