.CPP File Format – Standard library

C++ source code

The standard library is declared in namespace std, through headers named without an extension [headers]. This page lists every header of C++23 by group, and the standard that added it. A hosted implementation provides all of them; a freestanding one provides a subset. Headers shown as C++98 have been in the language since the first standard.

Modules

ModuleExportsSince
stdThe whole library, in namespace stdC++23
std.compatThe same, plus the C library names in the global namespaceC++23

See Namespaces and modules.

Language support

HeaderProvidesSince
<cfloat>Limits of floating-point types, as macrosC++98
<climits>Limits of integer types, as macrosC++98
<compare>Three-way comparison categoriesC++20
<coroutine>Coroutine supportC++20
<csetjmp>setjmp and longjmpC++98
<csignal>Signal handlingC++98
<cstdarg>Variable argumentsC++98
<cstddef>std::size_t, std::byte and related definitionsC++98
<cstdint>Fixed-width integer typesC++11
<cstdlib>General utilities from C, such as std::malloc and std::exitC++98
<exception>Exception handling supportC++98
<initializer_list>std::initializer_listC++11
<limits>std::numeric_limitsC++98
<new>Allocation functionsC++98
<source_location>std::source_locationC++20
<stdfloat>Extended floating-point aliasesC++23
<typeindex>std::type_indexC++11
<typeinfo>std::type_infoC++98
<version>Library feature-test macrosC++20

Concepts

HeaderProvidesSince
<concepts>The standard conceptsC++20

Diagnostics

HeaderProvidesSince
<cassert>The assert macroC++98
<cerrno>errnoC++98
<stacktrace>std::stacktraceC++23
<stdexcept>Standard exception typesC++98
<system_error>std::error_code and related typesC++11

Memory management

HeaderProvidesSince
<memory>Smart pointers and allocatorsC++98
<memory_resource>Polymorphic allocatorsC++17
<scoped_allocator>std::scoped_allocator_adaptorC++11

Metaprogramming

HeaderProvidesSince
<ratio>Compile-time rational arithmeticC++11
<type_traits>Type traitsC++11

General utilities

HeaderProvidesSince
<any>std::anyC++17
<bit>Bit manipulation and std::bit_castC++20
<bitset>std::bitsetC++98
<expected>std::expectedC++23
<functional>Function objects and std::functionC++98
<optional>std::optionalC++17
<tuple>std::tupleC++11
<utility>std::pair, std::move, std::forwardC++98
<variant>std::variantC++17

Containers

HeaderProvidesSince
<array>std::arrayC++11
<deque>std::dequeC++98
<flat_map>std::flat_map, std::flat_multimapC++23
<flat_set>std::flat_set, std::flat_multisetC++23
<forward_list>std::forward_listC++11
<list>std::listC++98
<map>std::map, std::multimapC++98
<mdspan>std::mdspanC++23
<queue>std::queue, std::priority_queueC++98
<set>std::set, std::multisetC++98
<span>std::spanC++20
<stack>std::stackC++98
<unordered_map>std::unordered_map, std::unordered_multimapC++11
<unordered_set>std::unordered_set, std::unordered_multisetC++11
<vector>std::vectorC++98

Iterators, ranges and algorithms

HeaderProvidesSince
<iterator>IteratorsC++98
<generator>std::generatorC++23
<ranges>Ranges and viewsC++20
<algorithm>General algorithmsC++98
<numeric>Numeric algorithmsC++98
<execution>Execution policies for parallel algorithmsC++17

Strings and text

HeaderProvidesSince
<cctype>Character classificationC++98
<charconv>std::to_chars, std::from_charsC++17
<clocale>C locale functionsC++98
<codecvt>Unicode conversion facets. Deprecated in C++17C++11
<cstring>C string and memory functionsC++98
<cuchar>C Unicode conversion functionsC++11
<cwchar>C wide-character functionsC++98
<cwctype>Wide-character classificationC++98
<format>std::formatC++20
<locale>LocalesC++98
<regex>Regular expressionsC++11
<string>std::basic_stringC++98
<string_view>std::basic_string_viewC++17

Numerics

HeaderProvidesSince
<cfenv>The floating-point environmentC++11
<cmath>Mathematical functionsC++98
<complex>Complex numbersC++98
<numbers>Mathematical constantsC++20
<random>Random number generationC++11
<valarray>Numeric arraysC++98

Time

HeaderProvidesSince
<chrono>Clocks, durations, and since C++20 calendars and time zonesC++11
<ctime>C time functionsC++98

Input and output

HeaderProvidesSince
<cinttypes>Format macros for fixed-width integersC++11
<cstdio>C input and outputC++98
<filesystem>std::filesystemC++17
<fstream>File streamsC++98
<iomanip>Stream manipulatorsC++98
<ios>Stream base classesC++98
<iosfwd>Forward declarations of the stream classesC++98
<iostream>std::cin, std::cout, std::cerrC++98
<istream>Input streamsC++98
<ostream>Output streamsC++98
<print>std::print, std::printlnC++23
<spanstream>Streams over a fixed bufferC++23
<sstream>String streamsC++98
<streambuf>Stream buffersC++98
<strstream>char* streams. Deprecated since C++98C++98
<syncstream>Synchronised output streamsC++20

Concurrency

HeaderProvidesSince
<atomic>Atomic operationsC++11
<barrier>std::barrierC++20
<condition_variable>std::condition_variableC++11
<future>std::future, std::promiseC++11
<latch>std::latchC++20
<mutex>std::mutex and locksC++11
<semaphore>std::counting_semaphoreC++20
<shared_mutex>std::shared_mutex and std::shared_lockC++14
<stop_token>std::stop_tokenC++20
<thread>std::thread, std::jthreadC++11

C compatibility headers

Each C standard header <name.h> can be included as it is. It declares its names in the global namespace, and may also declare them in std. The <cname> form declares them in std, and may also declare them globally.

HeadersSince
<assert.h> <ctype.h> <errno.h> <float.h> <limits.h> <locale.h> <math.h> <setjmp.h> <signal.h> <stdarg.h> <stddef.h> <stdio.h> <stdlib.h> <string.h> <time.h> <wchar.h> <wctype.h>C++98
<fenv.h> <inttypes.h> <stdint.h> <uchar.h>C++11
<stdatomic.h>C++23

Some C headers have no real content in C++:

HeaderStatus
<complex.h>, <tgmath.h>Include <complex> and, for the second, <cmath>
<ccomplex>, <ctgmath>Added in C++11, deprecated in C++17, removed in C++20
<iso646.h>Empty: the alternative tokens are built in
<ciso646>Removed in C++20
<stdalign.h>, <stdbool.h>Each defines one compatibility macro
<cstdalign>, <cstdbool>Added in C++11, deprecated in C++17, removed in C++20

The C headers <stdnoreturn.h> and <threads.h> are not part of C++.