Must new c++ Code be added from editor?

No u dont have to use Editor.

I am adding C++ code to my project by following steps:

  1. Create link to GenerateProjectFiles.bat, and change command line arguments of that link for generating files for my particular project: …GenerateProjectFiles.bat -Game “D:\Unreal Projects\MyProject\MyProject.uproject” -Engine
  2. Adding new folder/.cpp/.h files to my project, using any file manager.
  3. Launching (1) link.
  4. My new project files regenerated, if project is currently opened, then VisualStudio will ask me Reopen files, i press Reopen. Done.