Get File Attributes During Directory Iteration

Yes, std::filesystem::directory_iterator can be used to get various attributes of files and directories, such as size, type, and timestamps. The std::filesystem::directory_entry object provided by the iterator offers methods to retrieve these attributes.

Getting File Size and Type:

Here’s how you can get the size and type (file or directory) of each entry:

1#include <filesystem>
2#include <iostream>
3
4namespace fs = std::filesystem;
5
6int main() {
7  fs::directory_iterator start{R"(c:\test)"};
8  fs::directory_iterator end{};
9
10  for (auto iter{start}; iter != end; ++iter) {
11    std::cout << iter->path().string();
12    if (iter->is_directory()) {
13      std::cout << " (Directory)";
14    } else if (iter->is_regular_file()) {
15      std::cout << " (" << iter->file_size()
16        << " Bytes)";
17    }
18    std::cout << '\n';
19  }
20}

1c:\test\file1.txt (0 Bytes)
2c:\test\file2.txt (1024 Bytes)
3c:\test\directory (Directory)

Getting Timestamps:

You can also get timestamps like last modification time:

1#include <chrono>
2#include <ctime>
3#include <filesystem>
4#include <iostream>
5
6namespace fs = std::filesystem;
7
8int main() {
9  using namespace std::chrono;
10  fs::directory_iterator start{R"(c:\test)"};
11  fs::directory_iterator end{};
12
13  for (auto iter{start}; iter != end; ++iter) {
14    auto ftime = fs::last_write_time(iter->path());
15    auto sctp =
16      time_point_cast<system_clock::duration>(
17        ftime - fs::file_time_type::clock::now()
18        + system_clock::now());
19    std::time_t cftime =
20      system_clock::to_time_t(sctp);
21
22    std::cout << iter->path().string()
23      << " - Last Write Time: "
24      << std::asctime(std::localtime(&cftime));
25  }
26}

1c:\test\file1.txt - Last Write Time: Mon Jun 10 17:21:40 2024
2c:\test\file2.txt - Last Write Time: Mon Jun 10 17:21:40 2024
3c:\test\file2.txt - Last Write Time: Mon Jun 10 17:26:19 2024

Steps to Retrieve Attributes:

1. File Size: Use file_size() to get the size of regular files.
2. File Type: Use is_directory(), is_regular_file(), and other type-check methods.
3. Timestamps: Use last_write_time() to get the last modification time.

Advanced Attributes:

For more advanced attributes, like permissions or ownership, you might need platform-specific APIs. However, basic attributes are well-covered by the standard library.

By leveraging these methods, you can gather comprehensive details about files and directories as you iterate through them using std::filesystem::directory_iterator.