NAME¶

std::filesystem::recursive_directory_iterator - std::filesystem::recursive_directory_iterator

Synopsis¶

Defined in header <filesystem>
class recursive_directory_iterator; (since C++17)

recursive_directory_iterator is a LegacyInputIterator that iterates over the
directory_entry elements of a directory, and, recursively, over the entries of all
subdirectories. The iteration order is unspecified, except that each directory entry
is visited only once.

By default, symlinks are not followed, but this can be enabled by specifying the
directory option follow_directory_symlink at construction time.

The special pathnames dot and dot-dot are skipped.

If the recursive_directory_iterator reports an error or is advanced past the last
directory entry of the top-level directory, it becomes equal to the
default-constructed iterator, also known as the end iterator. Two end iterators are
always equal, dereferencing or incrementing the end iterator is undefined behavior.

If a file or a directory is deleted or added to the directory tree after the
recursive directory iterator has been created, it is unspecified whether the change
would be observed through the iterator.

If the directory structure contains cycles, the end iterator may be unreachable.

Member types¶

Member type Definition
value_type std::filesystem::directory_entry
difference_type std::ptrdiff_t
pointer const std::filesystem::directory_entry*
reference const std::filesystem::directory_entry&
iterator_category std::input_iterator_tag

Member functions¶

constructor constructs a recursive directory iterator
(public member function)
destructor default destructor
(public member function)

Observers¶

operator* accesses the pointed-to entry
operator-> (public member function)
returns the currently active options that affect the
options iteration
(public member function)
depth returns the current recursion depth
(public member function)
checks whether the recursion is disabled for the current
recursion_pending directory
(public member function)

Modifiers¶

operator= assigns contents
(public member function)
increment advances to the next entry
operator++ (public member function)
pop moves the iterator one level up in the directory hierarchy
(public member function)
disable_recursion_pending disables recursion until the next increment
(public member function)

Non-member functions¶

begin(std::filesystem::recursive_directory_iterator) range-based for loop support
end(std::filesystem::recursive_directory_iterator) (function)

Additionally,
operator== and operator!= are
(until C++20)
operator== is
(since C++20) provided as required by LegacyInputIterator.

It is unspecified
whether operator!= is provided because it can be synthesized from operator==, and
(since C++20) whether an equality operator is a member or non-member.

Helper templates

namespace std::ranges {

template<>
inline constexpr bool (since
enable_borrowed_range<std::filesystem::recursive_directory_iterator> = C++20)
true;

}
namespace std::ranges {

template<> (since
inline constexpr bool C++20)
enable_view<std::filesystem::recursive_directory_iterator> = true;

}

These specializations for recursive_directory_iterator make it a borrowed_range and
a view.

Notes¶

A recursive_directory_iterator typically holds a reference-counted pointer (to
satisfy shallow-copy semantics of LegacyInputIterator) to an implementation object,
which holds:

* a container (such as std::vector) of non-recursive directory_iterators that
forms the recursion stack,
* the recursion depth counter (accessible with depth()),
* the directory options used at construction (accessible with options()),
* the pending recursion flag (accessible with recursion_pending(), may be combined
with the directory options to save space).

Example¶

// Run this code

#include <filesystem>
#include <fstream>
#include <iostream>
#include <string>
namespace fs = std::filesystem;

int main()
{
std::filesystem::current_path(std::filesystem::temp_directory_path());
std::filesystem::create_directories("sandbox/a/b");
std::ofstream("sandbox/file1.txt");
std::filesystem::create_symlink("a", "sandbox/syma");

// Iterate over the std::filesystem::directory_entry elements explicitly
auto entry_length{3UZ};
for (const fs::directory_entry& dir_entry :
fs::recursive_directory_iterator("sandbox"))
{
std::cout << dir_entry << '\n';
if (auto l{dir_entry.path().string().length()}; entry_length < l)
entry_length = l;
}
std::cout << std::string(entry_length + 2, '-') << '\n';

// Iterate over the std::filesystem::directory_entry elements using `auto`
for (auto const& dir_entry : fs::recursive_directory_iterator("sandbox"))
std::cout << dir_entry << '\n';

std::filesystem::remove_all("sandbox");
}

Possible output:¶

"sandbox/syma"
"sandbox/file1.txt"
"sandbox/a"
"sandbox/a/b"
-------------------
"sandbox/syma"
"sandbox/file1.txt"
"sandbox/a"
"sandbox/a/b"

Defect reports

The following behavior-changing defect reports were applied retroactively to
previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 3480 C++20 recursive_directory_iterator was neither a it is both
borrowed_range nor a view

See also¶

directory_iterator an iterator to the contents of the directory
(C++17) (class)
directory_entry a directory entry
(C++17) (class)
directory_options options for iterating directory contents
(C++17) (enum)