std::filesystem::path::append, std::filesystem::path::operator/=

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

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::copy_options filesystem::directory_options filesystem::file_time_type
Functions
filesystem::absolute filesystem::system_complete 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::path

Member functions
path::path path::~path path::operator= path::assign path::appendpath::operator /= path::concatpath::operator += path::clear path::make_preferred path::remove_filename path::replace_filename path::replace_extension path::swap path::compare path::beginpath::end	path::c_strpath::nativepath::operator string_type path::stringpath::u8stringpath::u16stringpath::u32stringpath::wstring path::generic_stringpath::generic_u8stringpath::generic_u16stringpath::generic_u32stringpath::generic_wstring path::lexically_normalpath::lexically_relativepath::lexically_proximate
Path decomposition
path::root_name path::root_directory path::root_path path::relative_path path::parent_path path::filename path::stem path::extension path::empty	path::has_root_pathpath::has_root_namepath::has_root_directorypath::has_relative_pathpath::has_parent_pathpath::has_filenamepath::has_stempath::has_extension path::is_absolutepath::is_relative
Non-member functions
swap(path)
hash_value
operator==operator!=operator<operator<=operator>operator>=
operator/
operator<<operator>>
u8path

 

path& operator/=(const path& p);	(1)	(since C++17)
template< class Source > path& operator/=( const Source& source );	(2)	(since C++17)
template< class Source > path& append( const Source& source );	(3)	(since C++17)
template< class InputIt > path& append( InputIt first, InputIt last );	(4)	(since C++17)

1) First, appends the preferred directory separator to this, except if any of the following conditions is true:

* the separator would be redundant (*this already ends with a separator)

* *this is empty, or adding it would turn a relative path to an absolute path in some other way

* p is an empty path.

* p.native() begins with a directory separator.

Then, appends p.native() to the pathname maintained by *this

The behavior is undefined if p.has_root_name() is true.

2,3) Same as (1), but accepts any std::basic_string, std::basic_string_view, null-terminated multicharacter string, or an input iterator pointing to a null-terminated multicharacter sequence. Equivalent to return operator/=(path(source));.

4) Same as (1), but accepts any iterator pair that designates a multicharacter string. Equivalent to return operator/=(path(first, last));

Parameters

p	-	pathname to append
source	-	std::basic_string, std::basic_string_view, null-terminated multicharacter string, or an input iterator pointing to a null-terminated multicharacter sequence, which represents a path name (either in portable or in native format)
first, last	-	pair of InputIterators that specify a multicharacter sequence that represents a path name
Type requirements
- InputIt must meet the requirements of InputIterator.
- The value type of InputIt must be one of the encoded character types (char, wchar_t, char16_t and char32_t)

Return value

*this

Exceptions

May throw filesystem_error on underlying OS API errors or std::bad_alloc if memory allocation fails.

Example

Run this code

#include <iostream>
#include <filesystem>
namespace fs = std::filesystem;
int main() {
    fs::path p1 = "C:";
    p1 /= "Users"; // does not insert a separator
    std::cout << "\"C:\" / \"Users\" == " << p1 << '\n';
    p1 /= "batman"; // inserts fs::path::preferred_separator, '\' on Windows
    std::cout << "\"C:\" / \"Users\" / \"batman\" == " << p1 << '\n';
}

Possible output:

"C:" / "Users" == "C:Users"
"C:" / "Users" / "batman" == "C:Users\batman"

See also

concatoperator+=	concatenates two paths without introducing a directory separator (public member function)
operator/	concatenates two paths with a directory separator (function)