std::filesystem::directory_entry::assign

 

C++

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Freestanding and hosted

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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<<

 

void assign( const std::filesystem::path& p ); void assign( const std::filesystem::path& p, std::error_code& ec );		(since C++17)

Assigns new content to the directory entry object. Sets the path to p and calls refresh to update the cached attributes. If an error occurs, the values of the cached attributes are unspecified.

This function does not commit any changes to the filesystem.

Parameters

p	-	path to the filesystem object to which the directory entry will refer
ec	-	out-parameter for error reporting in the non-throwing overload

Return value

(none)

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>
 
void print_entry_info(const std::filesystem::directory_entry& entry)
{
    std::cout << "the entry " << entry;
    if (not entry.exists()) {
        std::cout << " does not exists on the file system\n";
        return;
    }
    std::cout << " is ";
    if (entry.is_directory()) std::cout << "a directory\n";
    if (entry.is_regular_file()) std::cout << "a regular file\n";
    /*...*/
}
 
int main()
{
    std::filesystem::current_path(std::filesystem::temp_directory_path());
 
    std::filesystem::directory_entry entry{std::filesystem::current_path()};
    print_entry_info(entry);
 
    std::filesystem::path name{"cppreference.html"};
    std::ofstream{name} << "C++";
 
    std::cout << "entry.assign();\n";
    entry.assign(entry/name);
    print_entry_info(entry);
 
    std::cout << "remove(entry);\n";
    std::filesystem::remove(entry);
    print_entry_info(entry); // the entry still contains old "state"
 
    std::cout << "entry.assign();\n";
    entry.assign(entry); // or just call entry.refresh()
    print_entry_info(entry);
}

Possible output:

the entry "/tmp" is a directory
entry.assign();
the entry "/tmp/cppreference.html" is a regular file
remove(entry);
the entry "/tmp/cppreference.html" is a regular file
entry.assign();
the entry "/tmp/cppreference.html" does not exists on the file system

See also

operator=

assigns contents (public member function)