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{{title|C++ Standard Library headers}}
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The interface of C++ standard library is defined by the following collection of headers.

{{dsc begin}}

{{dsc h1|Multi-purpose headers}}
{{dsc inc|cpp/header/dsc cstdlib}}
{{dsc inc|cpp/header/dsc execution}}

{{dsc h1|Language support library}}
{{dsc inc|cpp/header/dsc cfloat}}
{{dsc inc|cpp/header/dsc climits}}
{{dsc inc|cpp/header/dsc compare}}
{{dsc inc|cpp/header/dsc coroutine}}
{{dsc inc|cpp/header/dsc csetjmp}}
{{dsc inc|cpp/header/dsc csignal}}
{{dsc inc|cpp/header/dsc cstdarg}}
{{dsc inc|cpp/header/dsc cstddef}}
{{dsc inc|cpp/header/dsc cstdint}}
{{dsc inc|cpp/header/dsc exception}}
{{dsc inc|cpp/header/dsc initializer_list}}
{{dsc inc|cpp/header/dsc limits}}
{{dsc inc|cpp/header/dsc new}}
{{dsc inc|cpp/header/dsc source_location}}
{{dsc inc|cpp/header/dsc stdfloat}}
{{dsc inc|cpp/header/dsc typeindex}}
{{dsc inc|cpp/header/dsc typeinfo}}
{{dsc inc|cpp/header/dsc version}}

{{dsc h1|Concepts library}}
{{dsc inc|cpp/header/dsc concepts}}

{{dsc h1|Diagnostics library}}
{{dsc inc|cpp/header/dsc cassert}}
{{dsc inc|cpp/header/dsc cerrno}}
{{dsc inc|cpp/header/dsc debugging}}
{{dsc inc|cpp/header/dsc stacktrace}}
{{dsc inc|cpp/header/dsc stdexcept}}
{{dsc inc|cpp/header/dsc system_error}}

{{dsc h1|Memory management library}}
{{dsc inc|cpp/header/dsc memory}}
{{dsc inc|cpp/header/dsc memory_resource}}
{{dsc inc|cpp/header/dsc scoped_allocator}}

{{dsc h1|Metaprogramming library}}
{{dsc inc|cpp/header/dsc ratio}}
{{dsc inc|cpp/header/dsc type_traits}}

{{dsc h1|General utilities library}}
{{dsc inc|cpp/header/dsc any}}
{{dsc inc|cpp/header/dsc bit}}
{{dsc inc|cpp/header/dsc bitset}}
{{dsc inc|cpp/header/dsc expected}}
{{dsc inc|cpp/header/dsc functional}}
{{dsc inc|cpp/header/dsc optional}}
{{dsc inc|cpp/header/dsc tuple}}
{{dsc inc|cpp/header/dsc utility}}
{{dsc inc|cpp/header/dsc variant}}

{{dsc h1|Containers library}}
{{dsc inc|cpp/header/dsc array}}
{{dsc inc|cpp/header/dsc deque}}
{{dsc inc|cpp/header/dsc flat_map}}
{{dsc inc|cpp/header/dsc flat_set}}
{{dsc inc|cpp/header/dsc forward_list}}
{{dsc inc|cpp/header/dsc inplace_vector}}
{{dsc inc|cpp/header/dsc list}}
{{dsc inc|cpp/header/dsc map}}
{{dsc inc|cpp/header/dsc mdspan}}
{{dsc inc|cpp/header/dsc queue}}
{{dsc inc|cpp/header/dsc set}}
{{dsc inc|cpp/header/dsc span}}
{{dsc inc|cpp/header/dsc stack}}
{{dsc inc|cpp/header/dsc unordered_map}}
{{dsc inc|cpp/header/dsc unordered_set}}
{{dsc inc|cpp/header/dsc vector}}

{{dsc h1|Iterators library}}
{{dsc inc|cpp/header/dsc iterator}}

{{dsc h1|Ranges library}}
{{dsc inc|cpp/header/dsc generator}}
{{dsc inc|cpp/header/dsc ranges}}

{{dsc h1|Algorithms library}}
{{dsc inc|cpp/header/dsc algorithm}}
{{dsc inc|cpp/header/dsc numeric}}

{{dsc h1|Strings library}}
{{dsc inc|cpp/header/dsc cstring}}
{{dsc inc|cpp/header/dsc string}}
{{dsc inc|cpp/header/dsc string_view}}

{{dsc h1|Text processing library}}
{{dsc inc|cpp/header/dsc cctype}}
{{dsc inc|cpp/header/dsc charconv}}
{{dsc inc|cpp/header/dsc clocale}}
{{dsc inc|cpp/header/dsc codecvt}}
{{dsc inc|cpp/header/dsc cuchar}}
{{dsc inc|cpp/header/dsc cwchar}}
{{dsc inc|cpp/header/dsc cwctype}}
{{dsc inc|cpp/header/dsc format}}
{{dsc inc|cpp/header/dsc locale}}
{{dsc inc|cpp/header/dsc regex}}
{{dsc inc|cpp/header/dsc text_encoding}}

{{dsc h1|Numerics library}}
{{dsc inc|cpp/header/dsc cfenv}}
{{dsc inc|cpp/header/dsc cmath}}
{{dsc inc|cpp/header/dsc complex}}
{{dsc inc|cpp/header/dsc linalg}}
{{dsc inc|cpp/header/dsc numbers}}
{{dsc inc|cpp/header/dsc random}}
{{dsc inc|cpp/header/dsc valarray}}

{{dsc h1|Time library}}
{{dsc inc|cpp/header/dsc chrono}}
{{dsc inc|cpp/header/dsc ctime}}

{{dsc h1|Input/output library}}
{{dsc inc|cpp/header/dsc cinttypes}}
{{dsc inc|cpp/header/dsc cstdio}}
{{dsc inc|cpp/header/dsc filesystem}}
{{dsc inc|cpp/header/dsc fstream}}
{{dsc inc|cpp/header/dsc iomanip}}
{{dsc inc|cpp/header/dsc ios}}
{{dsc inc|cpp/header/dsc iosfwd}}
{{dsc inc|cpp/header/dsc iostream}}
{{dsc inc|cpp/header/dsc istream}}
{{dsc inc|cpp/header/dsc ostream}}
{{dsc inc|cpp/header/dsc print}}
{{dsc inc|cpp/header/dsc spanstream}}
{{dsc inc|cpp/header/dsc sstream}}
{{dsc inc|cpp/header/dsc streambuf}}
{{dsc inc|cpp/header/dsc strstream}}
{{dsc inc|cpp/header/dsc syncstream}}

{{dsc h1|Concurrency support library}}
{{dsc inc|cpp/header/dsc atomic}}
{{dsc inc|cpp/header/dsc barrier}}
{{dsc inc|cpp/header/dsc condition_variable}}
{{dsc inc|cpp/header/dsc future}}
{{dsc inc|cpp/header/dsc hazard_pointer}}
{{dsc inc|cpp/header/dsc latch}}
{{dsc inc|cpp/header/dsc mutex}}
{{dsc inc|cpp/header/dsc rcu}}
{{dsc inc|cpp/header/dsc semaphore}}
{{dsc inc|cpp/header/dsc shared_mutex}}
{{dsc inc|cpp/header/dsc stop_token}}
{{dsc inc|cpp/header/dsc thread}}
{{dsc end}}

===C compatibility headers===
For some of the C standard library headers of the form {{tt|''xxx''.h}}, the C++ standard library both includes an identically-named header and another header of the form {{tt|c''xxx''}} (all meaningful {{tt|c''xxx''}} headers are listed above). The intended use of headers of form {{tt|''xxx''.h}} is for interoperability only. It is possible that C++ source files need to include one of these headers in order to be valid ISO C. Source files that are not intended to also be valid ISO C should not use any of the C headers.

With the exception of {{rlt|ccomplex|complex.h}}{{mark unreviewed dr|LWG}}<!--LWG 551/2536-->, each {{tt|''xxx''.h}} header included in the C++ standard library places in the global namespace each name that the corresponding {{tt|c''xxx''}} header would have placed in the {{c|std}} namespace.

These headers are allowed to also declare the same names in the {{c|std}} namespace, and the corresponding {{tt|c''xxx''}} headers are allowed to also declare the same names in the global namespace: including {{header|cstdlib}} definitely provides {{lc|std::malloc}} and may also provide {{c/core|::malloc}}. Including {{header|stdlib.h|lang=c}} definitely provides {{c/core|::malloc}} and may also provide {{lc|std::malloc}}. This applies even to functions and function overloads that are not part of C standard library.

Notes: {{tt|''xxx''.h}} headers are deprecated in C++98 and undeprecated in C++23. These headers are discouraged for pure C++ code, but not subject to future removal.

{{dsc begin}}
{{dsc inc|cpp/header/dsc assert.h}}
{{dsc inc|cpp/header/dsc ctype.h}}
{{dsc inc|cpp/header/dsc errno.h}}
{{dsc inc|cpp/header/dsc fenv.h}}
{{dsc inc|cpp/header/dsc float.h}}
{{dsc inc|cpp/header/dsc inttypes.h}}
{{dsc inc|cpp/header/dsc limits.h}}
{{dsc inc|cpp/header/dsc locale.h}}
{{dsc inc|cpp/header/dsc math.h}}
{{dsc inc|cpp/header/dsc setjmp.h}}
{{dsc inc|cpp/header/dsc signal.h}}
{{dsc inc|cpp/header/dsc stdarg.h}}
{{dsc inc|cpp/header/dsc stddef.h}}
{{dsc inc|cpp/header/dsc stdint.h}}
{{dsc inc|cpp/header/dsc stdio.h}}
{{dsc inc|cpp/header/dsc stdlib.h}}
{{dsc inc|cpp/header/dsc string.h}}
{{dsc inc|cpp/header/dsc time.h}}
{{dsc inc|cpp/header/dsc uchar.h}}
{{dsc inc|cpp/header/dsc wchar.h}}
{{dsc inc|cpp/header/dsc wctype.h}}
{{dsc end}}

====Special C compatibility headers====
The header {{header|stdatomic.h|lang=c}} declares names which are also provided in the C standard library, and defines the {{tt|_Atomic}} macro which is a [[c/keyword/_Atomic|keyword]] in C. Unlike other {{tt|''xxx''.h}} headers, corresponding {{tt|<cstdatomic>}} is not provided.

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{{dsc inc|cpp/header/dsc stdatomic.h}}
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====Empty C headers====
The headers {{header|complex.h|lang=c}}, {{header|ccomplex}}, {{header|tgmath.h|lang=c}}, and {{header|ctgmath}} do not contain any content from the C standard library and instead merely include other headers from the C++ standard library.

{{dsc begin}}
{{dsc inc|cpp/header/dsc ccomplex}}
{{dsc inc|cpp/header/dsc complex.h}}
{{dsc inc|cpp/header/dsc ctgmath}}
{{dsc inc|cpp/header/dsc tgmath.h}}
{{dsc end}}

====Meaningless C headers====
The headers {{header|ciso646}}, {{header|cstdalign}}, and {{header|cstdbool}} are meaningless in C++ because the macros they provide in C are language keywords in C++.

{{dsc begin}}
{{dsc inc|cpp/header/dsc ciso646}}
{{dsc inc|cpp/header/dsc cstdalign}}
{{dsc inc|cpp/header/dsc cstdbool}}
{{dsc inc|cpp/header/dsc iso646.h}}
{{dsc inc|cpp/header/dsc stdalign.h}}
{{dsc inc|cpp/header/dsc stdbool.h}}
{{dsc end}}

====Unsupported C headers====
The C headers {{rev inl|until=c++23|{{header|stdatomic.h|lang=c}},}} {{header|stdnoreturn.h|lang=c}}, and {{header|threads.h|lang=c}} are not included in C++ and have no {{tt|c''xxx''}} equivalents.

==={{rl|experimental|Experimental libraries}}===
[[cpp/experimental|C++ TR's/TS's]] also define several collections of headers.

===See also===
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{{dsc see c|c/header|C Standard Library headers|nomono=true}}
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