filesystem

https://stackoverflow.com/questions/39231363/fatal-error-filesystem-no-such-file-or-directory

It seems you have to include like this:

#include <experimental/filesystem>

Don't forget to add -lstdc++fs as a GCC flag!

Here is the proof: Coliru

If that doesn't work, then that probably means that you don't have filesystem in your configuration.

Also, as @MartinR. pointed out, the experimental is no longer needed in GCC 8+.