std::filesystem::path::root_directory(3)

NAME
std::filesystem::path::root_directory - std::filesystem::path::root_directory

Synopsis
   path root_directory() const; (since C++17)
   Returns the root directory of the generic-format path. If the path (in generic
   format) does not include root directory, returns path().

Parameters
   (none)

Return value
   The root directory of the path.

Exceptions
   May throw implementation-defined exceptions.

Example
// Run this code
 #include <filesystem>
 #include <iostream>
 namespace fs = std::filesystem;
 int main()
 {
     fs::path p = fs::current_path();
     std::cout << "The current path " << p << " decomposes into:\n"
               << "root name " << p.root_name() << '\n'
               << "root directory " << p.root_directory() << '\n'
               << "relative path " << p.relative_path() << '\n';
 }

Possible output:
 The current path "C:\Users\abcdef\Local Settings\temp" decomposes into:
 root name "C:"
 root directory "\"
 relative path "Users\abcdef\Local Settings\temp"

See also
   root_name returns the root-name of the path, if present
             (public member function)
   root_path returns the root path of the path, if present
             (public member function)