std::filesystem::path::extension

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

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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::canonical 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::append path::concatpath::operator += path::clear path::make_preferred path::remove_filename path::replace_filename path::replace_extension path::swap path::compare	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::beginpath::end
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 extension() const;		(since C++17)

Returns the extension of the filename component of the path *this.

If the filename() component of the path contains a period (.), and is not one of the special filesystem elements dot or dot-dot, then the extension is the substring beginning at the rightmost period (including the period) and until the end of the pathname.

If the pathname is either . or .., or if filename() does not contain the . character, then empty path is returned.

Additional behavior may be defined by the implementations for file systems which append additional elements (such as alternate data streams or partitioned dataset names) to extensions.

Parameters

(none)

Return value

The extension of the current pathname or an empty path if there's no extension.

Exceptions

(none)

Notes

The extension as returned by this function includes a period to make it possible to distinguish the file that ends with a period (function returns ".") from a file with no extension (function returns "")

For any path p, p.stem()+p.extension() == p.filename()

Example

Run this code

#include <iostream>
#include <filesystem>
namespace fs = std::filesystem;
 
int main()
{
    std::cout << fs::path("/foo/bar.txt").extension() << '\n'
              << fs::path("/foo/bar.").extension() << '\n'
              << fs::path("/foo/bar").extension() << '\n'
              << fs::path("/foo/bar.txt/bar.cc").extension() << '\n'
              << fs::path("/foo/bar.txt/bar.").extension() << '\n'
              << fs::path("/foo/bar.txt/bar").extension() << '\n'
              << fs::path("/foo/.").extension() << '\n'
              << fs::path("/foo/..").extension() << '\n'
              << fs::path("/foo/.hidden").extension() << '\n';
}

Output:

".txt"
"."
""
".cc"
"."
""
""
""
".hidden"

See also

filename	returns the filename path component (public member function)
stem	returns the stem path component (public member function)
replace_extension	replaces the extension (public member function)
has_extension	checks if the corresponding path element is not empty (public member function)