std::filesystem::is_empty - cppreference.com (original) (raw)

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

[edit] Parameters

[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 #include #include #include   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 << "cppreference.com"; file.flush(); std::cout << "is_empty(): " << fs::is_empty(tmp_name) << '\n' << "file_size(): " << fs::file_size(tmp_name) << '\n'; file.close(); fs::remove(tmp_name); }

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.

[edit] See also

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