std::filesystem::directory_entry::exists

 

C++

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Standard library headers

Named requirements

Feature test macros (C++20)

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Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

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Strings library

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Ranges library (C++20)

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Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Filesystem library

Classes
filesystem::path filesystem::filesystem_error filesystem::directory_entry filesystem::directory_iterator filesystem::recursive_directory_iterator      filesystem::file_status	filesystem::space_info filesystem::file_type filesystem::perms filesystem::perm_options filesystem::copy_options filesystem::directory_options filesystem::file_time_type
Functions
filesystem::absolute filesystem::canonicalfilesystem::weakly_canonical filesystem::relativefilesystem::proximate filesystem::copy filesystem::copy_file filesystem::copy_symlink filesystem::create_directory filesystem::create_directories filesystem::create_hard_link filesystem::create_symlink filesystem::create_directory_symlink filesystem::current_path	filesystem::exists filesystem::equivalent filesystem::file_size filesystem::hard_link_count filesystem::last_write_time filesystem::permissions filesystem::read_symlink filesystem::remove filesystem::remove_all filesystem::rename filesystem::resize_file filesystem::space filesystem::status filesystem::symlink_status filesystem::temp_directory_path
File types
filesystem::is_block_file filesystem::is_character_file filesystem::is_directory filesystem::is_empty filesystem::status_known	filesystem::is_fifo filesystem::is_other filesystem::is_regular_file filesystem::is_socket filesystem::is_symlink

 

std::filesystem::directory_entry

Member functions

directory_entry::directory_entry

Modifiers

directory_entry::operator=

directory_entry::assign

directory_entry::replace_filename

directory_entry::refresh

Observers

directory_entry::pathdirectory_entry::operator const path&

directory_entry::exists

directory_entry::is_block_file

directory_entry::is_character_file

directory_entry::is_directory

directory_entry::is_fifo

directory_entry::is_other

directory_entry::is_regular_file

directory_entry::is_socket

directory_entry::is_symlink

directory_entry::file_size

directory_entry::hard_link_count

directory_entry::last_write_time

directory_entry::statusdirectory_entry::symlink_status

directory_entry::operator==directory_entry::operator!=directory_entry::operator<directory_entry::operator>directory_entry::operator<=directory_entry::operator>=directory_entry::operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

Non-member functions

operator<<

 

bool exists() const; bool exists( std::error_code& ec ) const noexcept;		(since C++17)

Checks whether the pointed-to object exists. Effectively returns std::filesystem::exists(status()) or std::filesystem::exists(status(ec)), respectively.

Parameters

ec

-

out-parameter for error reporting in the non-throwing overload

Return value

true if the referred-to filesystem object exists.

Exceptions

The overload that does not take a std::error_code& parameter throws filesystem::filesystem_error on underlying OS API errors, constructed with p as the first path argument and the OS error code as the error code argument. The overload taking a std::error_code& parameter sets it to the OS API error code if an OS API call fails, and executes ec.clear() if no errors occur. Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.

Example

Run this code

#include <filesystem>
#include <fstream>
#include <iostream>
#include <string>
 
namespace fs = std::filesystem;
 
int main()
{
    // store current path to restore it at exit
    const auto old_current_path = fs::current_path();
 
    // create "sanbox" directory in temp dir
    const auto dir_sandbox = fs::temp_directory_path() / "sandbox";
 
    if (!fs::create_directory(dir_sandbox)) {
        std::cout << "ERROR #1" << '\n';
        return -1;
    }
 
    fs::current_path(dir_sandbox); // switch to newly created dir
 
    fs::directory_entry entry_sandbox { dir_sandbox };
    if (!entry_sandbox.exists()) {
        std::cout << "ERROR #2" << '\n';
        return -1;
    }
 
    std::cout << "Current dir: " << entry_sandbox.path().filename() << '\n';
 
    fs::path path_tmp_file = dir_sandbox / "tmp_file";
 
    std::ofstream file( path_tmp_file.string() ); // create regular file
    file << "cppreference.com"; // write 16 bytes
    file.flush();
 
    fs::directory_entry entry_tmp_file{ path_tmp_file };
 
    if (entry_tmp_file.exists()) {
        std::cout << "File " << entry_tmp_file.path().filename()
                  << " has size: " << entry_tmp_file.file_size() << '\n';
    } else {
        std::cout << "ERROR #3" << '\n';
    }
 
    // cleanup
    fs::current_path(old_current_path);
    fs::remove_all(dir_sandbox);
}

Possible output:

Current dir: "sandbox"
File "tmp_file" has size: 16

See also

exists (C++17)

checks whether path refers to existing file system object (function)