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 );

std::uintmax_t hard_link_count( const std::filesystem::path& p, (1) (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¶

The overload that does not take a std::error_code& parameter throws
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. The overload
taking a std::error_code& parameter sets it to the OS API error code if an OS API
call fails, and executes ec.clear() if no errors occur. Any overload not marked
noexcept may throw std::bad_alloc if memory allocation fails.

Example¶

// Run this code

#include <iostream>
#include <filesystem>
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)