Root directory for files?

Hi all can anyone tell me where is the root directory for files ? I want to open an text file however I can’t find the root directory in c++ it is normally the folder where the .sln file is located so you can just glue a path together like: root/assets/textfile.txt or do I have to add my text file into unreal project ? I’m working in c++ no blueprints etc.

never mind got it sorted heh the entire path is needed including drive letter