How can I skip certain files or directories during iteration?

Question

Ryan McCombe · Accepted Answer

To skip certain files or directories during iteration, you can use conditional statements within your loop. By checking the properties of each entry, you can decide whether to process it or skip it.

Here's an example where we skip files with a specific extension and directories with a specific name:

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    if (iter->is_directory() &&
12      iter->path().filename() == "skip_this_dir") {
13      continue;  // Skip this directory 
14    }
15    if (iter->is_regular_file() &&
16      iter->path().extension() == ".skip") {
17      continue;  // Skip files with .skip extension 
18    }
19    std::cout << iter->path().string() << '\n';
20  }
21}

1c:\test\file1.txt
2c:\test\file2.txt
3c:\test\another_directory

Steps to Skip Entries:

Check Directory Properties: Use is_directory() to check if the entry is a directory and path().filename() to get its name.
Check File Properties: Use is_regular_file() to check if the entry is a file and path().extension() to get its extension.
Skip Logic: Use continue to skip the current iteration if the conditions are met.

More Complex Filtering:

For more complex conditions, consider using a predicate function:

1#include <filesystem>
2#include <iostream>
3
4namespace fs = std::filesystem;
5
6bool should_skip(const fs::directory_entry& entry) {
7  if (entry.is_directory() &&
8    entry.path().filename() == "skip_this_dir") {
9    return true;
10  }
11  if (entry.is_regular_file() &&
12    entry.path().extension() == ".skip") {
13    return true;
14  }
15  return false;
16}
17
18int main() {
19  fs::directory_iterator start{R"(c:\test)"};
20  fs::directory_iterator end{};
21
22  for (auto iter{start}; iter != end; ++iter) {
23    if (should_skip(*iter)) {
24      continue;
25    }
26    std::cout << iter->path().string() << '\n';
27  }
28}

1c:\test\file1.txt
2c:\test\file2.txt
3c:\test\another_directory

This approach allows you to encapsulate the skip logic in a separate function, making your main loop cleaner and easier to read. Skipping certain files or directories during iteration is a common requirement and can be handled efficiently with these techniques.

Directory Iterators

Skip Files or Directories using `directory_iterator`

Steps to Skip Entries:

More Complex Filtering:

Directory Iterators

Professional C++

Questions & Answers

Skip Files or Directories using directory_iterator

Steps to Skip Entries:

More Complex Filtering:

Directory Iterators

Questions & Answers

Skip Files or Directories using `directory_iterator`