std::filesystem::hard_link_count(3)

NAME
std::filesystem::hard_link_count - std::filesystem::hard_link_count

Synopsis
   Defined in header <filesystem>
   std::uintmax_t hard_link_count( const std::filesystem::path& p ); (1) (since C++17)
   std::uintmax_t hard_link_count( const std::filesystem::path& p, (2) (since C++17)
                        std::error_code& ec ) noexcept;
   Returns the number of hard links for the filesystem object identified by path p.
   The non-throwing overload returns static_cast<uintmax_t>(-1) on errors.

Parameters
   p - path to examine
   ec - out-parameter for error reporting in the non-throwing overload

Return value
   The number of hard links for p.

Exceptions
   Any overload not marked noexcept may throw std::bad_alloc if memory allocation
   fails.
   1) Throws std::filesystem::filesystem_error on underlying OS API errors, constructed
   with p as the first path argument and the OS error code as the error code argument.
   2) Sets a std::error_code& parameter to the OS API error code if an OS API call
   fails, and executes ec.clear() if no errors occur.

Example
// Run this code
 #include <filesystem>
 #include <iostream>
 namespace fs = std::filesystem;
 int main()
 {
     // On a POSIX-style filesystem, each directory has at least 2 hard links:
     // itself and the special member pathname "."
     fs::path p = fs::current_path();
     std::cout << "Number of hard links for current path is "
               << fs::hard_link_count(p) << '\n';
     // Each ".." is a hard link to the parent directory, so the total number
     // of hard links for any directory is 2 plus number of direct subdirectories
     p = fs::current_path() / ".."; // Each dot-dot is a hard link to parent
     std::cout << "Number of hard links for .. is "
               << fs::hard_link_count(p) << '\n';
 }

Possible output:
 Number of hard links for current path is 2
 Number of hard links for .. is 3

See also
   create_hard_link creates a hard link
   (C++17) (function)
                    returns the number of hard links referring to the file to which the
   hard_link_count directory entry refers
                    (public member function of std::filesystem::directory_entry)