std::filesy...is_directory(3)

💖 NAME 💖

okay bestie, welcome to the std::filesystem::is_directory manual page — manual name std::filesy...is_directory(3), from the C++ Standard Libary ✨. It’s literally the std::filesystem::is_directory page, and we’re about to make directory checks feel iconic. 💅

✨ Synopsis ✨

Defined in header <filesystem>.

The overload lineup is:

• (1) (since C++17) — bool is_directory( std::filesystem::file_status s ) noexcept;
• (2) (since C++17) — bool is_directory( const std::filesystem::path& p );
• (3) (since C++17) — bool is_directory( const std::filesystem::path& p, std::error_code& ec ) noexcept;

Checks if the given file status or path corresponds to a directory. periodt.

1) Equivalent to s.type() == file_type::directory.

2,3) Equivalent to is_directory(status(p)) or is_directory(status(p, ec)), respectively.

🥺 Parameters 🥺

• s — file status to check
• p — path to query
• ec — error code to modify in case of errors

💖 Return value 💖

true if the file indicated by p or if the type indicated s refers to a directory, false otherwise. The non-throwing overload returns false if an error occurs.

😭 Exceptions 😭

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

2,3) Sets a std::error_code& parameter to the OS API error code if an OS API call fails, and executes ec.clear() if no errors occur.

🌸 Example 🌸

The page has a lil’ // Run this code link right here, so go run it bestie 🫶:

#include <cstdio>
#include <cstring>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <unistd.h>

namespace fs = std::filesystem;

void demo_status(const fs::path& p, fs::file_status s)
{
    std::cout << p;
    // alternative: switch(s.type()) { case fs::file_type::regular: ...}
    if (fs::is_regular_file(s))
        std::cout << " is a regular file\n";
    if (fs::is_directory(s))
        std::cout << " is a directory\n";
    if (fs::is_block_file(s))
        std::cout << " is a block device\n";
    if (fs::is_character_file(s))
        std::cout << " is a character device\n";
    if (fs::is_fifo(s))
        std::cout << " is a named IPC pipe\n";
    if (fs::is_socket(s))
        std::cout << " is a named IPC socket\n";
    if (fs::is_symlink(s))
        std::cout << " is a symlink\n";
    if (!fs::exists(s))
        std::cout << " does not exist\n";
}

int main()
{
    // create files of different kinds
    fs::create_directory("sandbox");
    fs::create_directory("sandbox/dir");
    std::ofstream{"sandbox/file"}; // create regular file
    fs::create_symlink("file", "sandbox/symlink");

    mkfifo("sandbox/pipe", 0644);
    sockaddr_un addr;
    addr.sun_family = AF_UNIX;
    std::strcpy(addr.sun_path, "sandbox/sock");
    int fd = socket(PF_UNIX, SOCK_STREAM, 0);
    bind(fd, reinterpret_cast<sockaddr*>(&addr), sizeof addr);

    // demo different status accessors
    for (auto it{fs::directory_iterator("sandbox")}; it != fs::directory_iterator(); ++it)
        demo_status(*it, it->symlink_status()); // use cached status from directory entry
    demo_status("/dev/null", fs::status("/dev/null")); // direct calls to status
    demo_status("/dev/sda", fs::status("/dev/sda"));
    demo_status("sandbox/no", fs::status("/sandbox/no"));

    // cleanup (prefer std::unique_ptr-based custom deleters)
    close(fd);
    fs::remove_all("sandbox");
}

🦋 Possible output 🦋

"sandbox/file" is a regular file
"sandbox/dir" is a directory
"sandbox/pipe" is a named IPC pipe
"sandbox/sock" is a named IPC socket
"sandbox/symlink" is a symlink
"/dev/null" is a character device
"/dev/sda" is a block device
"sandbox/no" does not exist

👑 See also 👑

• status — determines file attributes · (C++17) · function
• symlink_status — determines file attributes, checking the symlink target · (C++17) · function
• file_status — represents file type and permissions · (C++17) · class
• status_known — checks whether file status is known · (C++17) · function
• is_block_file — checks whether the given path refers to block device · (C++17) · function
• is_character_file — checks whether the given path refers to a character device · (C++17) · function
• is_fifo — checks whether the given path refers to a named pipe · (C++17) · function
• is_other — checks whether the argument refers to an other file · (C++17) · function
• is_regular_file — checks whether the argument refers to a regular file · (C++17) · function
• is_socket — checks whether the argument refers to a named IPC socket · (C++17) · function
• is_symlink — checks whether the argument refers to a symbolic link · (C++17) · function
• exists — checks whether path refers to existing file system object · (C++17) · function
• is_directory — checks whether the directory entry refers to a directory · public member function of std::filesystem::directory_entry

and that’s the whole page, bestie 🌈 — source: http://cppreference.com, version/date: 2024.06.10, page tag: std::filesy...is_directory(3). mwah 💋