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Showing content from https://en.cppreference.com/w/cpp/algorithm/../../cpp/symbol_index/../filesystem/is_empty.html below:

std::filesystem::is_empty - cppreference.com

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

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.

Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.

Throws

on underlying OS API errors, constructed with

as the first path argument and the OS error code as the error code argument.

Sets a

parameter to the OS API error code if an OS API call fails, and executes

if no errors occur.

#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 << "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

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