With C++17 (or Boost::filesystem), we can get the current path / current working directory using filesystem::current_path(). However - that gives us an absolute path.
We could also use an empty path as the relative current path - sometimes.
But - is it possible to obtain, portably, the equivalent of "." or "./" ? i.e. a non-empty relative current path?
"." for the current directory.std::filesystem will recognize "." as representing the current directory / path - regardless of the platform you're on. So, it will not just happen to work on Linux/Windows, it is guaranteed to work.
auto relative_current path = std::filesystem::path{"."};
Relevant wording in the standard: fs.path.generic.3.
This answer is basically due to @NathanOliver...