Filesystem in C++17

Upper we have seen a tiny use case for std::filesystem::path. That is a quite powerful and convenient feature that supplies an multi-platform abstraction for paths to files using the correct directory path separator depending on the platform we are building our application for (\ for Windows based systems and / for Unix based systems).

When we want our application to use the correct directory separator in C++11, we could use conditional macro declaration:

Compile and run: C++11 separator example.

Compile and run: C++17 separator example.

std::filesystem::path implements / operator, which allows to easily concatenate paths to files and directories.

When we want to concatenate paths in C++11, we have to add extra logic to avoid adding duplicate separators and to select the correct separator for target platform:

Checking program output we notice it is not fully correct, we should have checked whether path parts already contains a separator so we don’t append another separator again. That logic is already implemented in std::filesystem::path, so C++17 can be like:

Code is cleaner and just correct, there are no duplicated separators.

std::filesystem comes with some utilities to create and remove files and directories, but firstly let’s try to do so in C++11.

We have to create/remove one by one. We could rewrite this code snippet with less lines (using a loop), but we still have to pay attention to creation/deletion order, we cannot remove parent directory before we have removed all children.

Since C++17, we can create and remove nested directories with just one call.