Defined in header <filesystem>
bool is_empty( const std::filesystem::path& p );
(1) (since C++17)
bool is_empty( const std::filesystem::path& p, std::error_code& ec );
(2) (since C++17)

Checks whether the given path refers to an empty file or directory.


[edit] Parameters

p - path to examine
ec - error code to modify in case of error

[edit] Return value

true if the path indicated by p refers to an empty file or directory, false otherwise. The non-throwing overload returns false if an error occurs.

[edit] 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.

[edit] Example

#include <cstdio>
#include <filesystem>
#include <fstream>
#include <iostream>
int main()
    namespace fs = std::filesystem;
    const fs::path tmp_dir{fs::temp_directory_path()};
    std::cout << std::boolalpha
              << "Temp dir: " << tmp_dir << '\n'
              << "is_empty(): " << fs::is_empty(tmp_dir) << '\n';
    const fs::path tmp_name{tmp_dir / std::tmpnam(nullptr)};
    std::cout << "Temp file: " << tmp_name << '\n';
    std::ofstream file{tmp_name.string()};
    std::cout << "is_empty(): " << fs::is_empty(tmp_name) << '\n';
    file << "";
    std::cout << "is_empty(): " << fs::is_empty(tmp_name) << '\n'
              << "file_size(): " << fs::file_size(tmp_name) << '\n';

Possible output:

Temp dir: "/tmp"
is_empty(): false
Temp file: "/tmp/fileCqd9DM"
is_empty(): true
is_empty(): false
file_size(): 16

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 3013 C++17 error_code overload marked noexcept but can allocate memory noexcept removed

[edit] See also

determines file attributes
determines file attributes, checking the symlink target
(function) [edit]
checks whether path refers to existing file system object
(function) [edit]