List regular files recursively in sorted order.

C++: Collect relative paths before sorting because directory iteration order is unspecified.

C++ snippet.cpp
#include <iostream>
#include <string>
#include <string_view>
#include <vector>
#include <array>
#include <algorithm>
#include <numeric>
#include <map>
#include <unordered_map>
#include <set>
#include <queue>
#include <stack>
#include <deque>
#include <tuple>
#include <bitset>
#include <memory>
#include <optional>
#include <variant>
#include <functional>
#include <charconv>
#include <regex>
#include <fstream>
#include <sstream>
#include <filesystem>
#include <iomanip>
#include <cmath>
#include <cctype>
#include <limits>
#include <chrono>
#include <thread>
#include <future>
#include <mutex>
#include <atomic>
#include <condition_variable>

int main() {
    std::cout << std::boolalpha;
    std::vector<std::string> paths;
    for (const auto& entry:std::filesystem::recursive_directory_iterator("src")) {
        if (entry.is_regular_file()) paths.push_back(std::filesystem::relative(entry.path(),"src").generic_string());
    }
    std::sort(paths.begin(),paths.end());
    for (const auto& path:paths) std::cout << path << "\n";
}

Expected output EXAMPLE

a.txt
sub/b.txt

Details

Save as snippet.cpp; compile with g++ -std=c++17 -Wall -Wextra snippet.cpp -pthread -o snippet, then run ./snippet. Collect relative paths before sorting because directory iteration order is unspecified.

✓ Verified

Tested on Ubuntu 24.04.5 LTS · · g++ (Ubuntu 13.3.0-6ubuntu2~24.04.1) 13.3.0 · g++ 4:13.2.0-7ubuntu1

Test inputs, results and environment

The exact published code ran in a dedicated Linux test container with prepared inputs. Unprivileged snippet process, external networking disabled, read-only root filesystem, and a fresh temporary working directory. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.

Architecture / host kernel
x86_64 / 6.18.54.1-microsoft-standard-WSL2
Snippet identity / locale
uid=65534, gid=65534 (unprivileged) / C.UTF-8
Interpreter invocation
g++ -std=c++17 -Wall -Wextra -Werror snippet.cpp -pthread -lm -o snippet && ./snippet
Container image ID
sha256:32dc2d998158b6554c99b73b533f423696a0f3e31e8cbea9db10b5eee9a2fadd
Code SHA-256
3c1e4103dd0fb6006113569ef6d275da15e410fb88d237f12d62bed3ebbb0df1
Dependencies
g++ 4:13.2.0-7ubuntu1

Test input setup

These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.

mkdir -p src/sub; touch src/a.txt src/sub/b.txt

Observed standard output

a.txt
sub/b.txt

Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.