std::filesy...egular_file(3)

okay bestie, welcome to the manual page for std::filesy...egular_file(3) from the C++ Standard Library ✨ This is the little icon that checks whether a file status or path is giving regular-file energy 🎀

💖 NAME 💖

std::filesystem::is_regular_file — std::filesystem::is_regular_file

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🌸 Synopsis 🌸

Defined in header <filesystem> ✨

Defined in header <filesystem>
bool is_regular_file( std::filesystem::file_status s ) noexcept;
(1) (since C++17)
bool is_regular_file( const std::filesystem::path& p );
(2) (since C++17)
bool is_regular_file( const std::filesystem::path& p,
(3) (since C++17)
std::error_code& ec ) noexcept;

The labels are exactly where the manpage put ’em, no cap 🫶

Checks if the given file status or path corresponds to a regular file 💅

• 1) Equivalent to s.type() == file_type::regular. 🎀
• 2,3) Equivalent to is_regular_file(status(p)) or is_regular_file(status(p, ec)) respectively. 🌈

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🎀 Parameters 🎀

• s — file status to check 💖
• p — path to examine 🦋
• ec — error code to store the error status to 💅

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✨ Return value ✨

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

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💅 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. 🫶

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🦋 Notes 🦋

The throwing overload is additionally specified to throw std::filesystem::filesystem_error if status(p) would throw. 🚨

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🍓 Example 🍓

// Run this code

#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");
}

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🌈 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

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👑 See also 👑

• file_type — the type of a file ((C++17) (enum)) 👑
• 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_directory — checks whether the given path refers to a directory ((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_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_regular_file — checks whether the directory entry refers to a regular file (public member function of std::filesystem::directory_entry) 💖

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Source/version + date, bestie: http://cppreference.com, 2024.06.10, and the manual page is std::filesy...egular_file(3). That’s the whole vibe check, periodt 💅✨🫶