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{{title|Utility library}}
{{cpp/utility/navbar}}

C++ includes a variety of utility libraries that provide functionality ranging from [[cpp/utility/bitset|bit-counting]] to [[cpp/utility/functional/bind|partial function application]]. These libraries can be broadly divided into two groups:

* language support libraries, and
* general-purpose libraries.

==Language support==
Language support libraries provide classes and functions that interact closely with language features and support common language idioms.

===[[cpp/types|Type support]]===
Basic types (e.g. {{lc|std::size_t}}, {{lc|std::nullptr_t}}), RTTI (e.g. {{lc|std::type_info}})

===[[cpp/meta|Metaprogramming]]===
Type traits (e.g. {{lc|std::is_integral}}, {{lc|std::rank}}), compile-time constants (e.g. {{lc|std::integer_sequence}}, {{lc|std::ratio}})

===Constant evaluation context===
{{dsc begin}}
{{dsc header|type_traits}}
{{dsc inc|cpp/types/dsc is_constant_evaluated}}
{{dsc inc|cpp/types/dsc is_within_lifetime}}
{{dsc end}}

===[[cpp/utility/feature_test|Implementation properties]]===
{{rrev|since=c++20|
The header {{header|version}} supplies implementation-dependent information about the C++ standard library (such as the version number and release date). It also defines the [[cpp/utility/feature test|library feature-test macros]].
}}

===[[cpp/utility/program|Program utilities]]===
Termination (e.g. {{lc|std::abort}}, {{lc|std::atexit}}), environment (e.g. {{lc|std::system}}), signals (e.g. {{lc|std::raise}})

===[[cpp/memory|Dynamic memory management]]===
Smart pointers (e.g. {{lc|std::shared_ptr}}), allocators (e.g. {{lc|std::allocator}} or {{lc|std::pmr::memory_resource}}), C-style memory management (e.g. {{lc|std::malloc}})

===[[cpp/error|Error handling]]===
Exceptions (e.g. {{lc|std::exception}}, {{lc|std::terminate}}), assertions (e.g. {{lc|assert}})

===[[cpp/utility/source_location|Source code information capture]]===
{{dsc begin}}
{{dsc header|source_location}}
{{dsc inc|cpp/utility/dsc source_location}}
{{dsc end}}

===[[cpp/utility/initializer_list|Initializer lists]]===
{{dsc begin}}
{{dsc header|initializer_list}}
{{dsc inc|cpp/utility/dsc initializer_list}}
{{dsc end}}

===Three-way comparison===
{{dsc begin}}
{{dsc header|compare}}
{{dsc inc|cpp/utility/compare/dsc three_way_comparable}}
{{dsc inc|cpp/utility/compare/dsc partial_ordering}}
{{dsc inc|cpp/utility/compare/dsc weak_ordering}}
{{dsc inc|cpp/utility/compare/dsc strong_ordering}}
{{dsc inc|cpp/utility/compare/dsc named_comparison_functions}}
{{dsc inc|cpp/utility/compare/dsc compare_three_way}}
{{dsc inc|cpp/utility/compare/dsc compare_three_way_result}}
{{dsc inc|cpp/utility/compare/dsc common_comparison_category}}
{{dsc inc|cpp/utility/compare/dsc strong_order}}
{{dsc inc|cpp/utility/compare/dsc weak_order}}
{{dsc inc|cpp/utility/compare/dsc partial_order}}
{{dsc inc|cpp/utility/compare/dsc compare_strong_order_fallback}}
{{dsc inc|cpp/utility/compare/dsc compare_weak_order_fallback}}
{{dsc inc|cpp/utility/compare/dsc compare_partial_order_fallback}}
{{dsc end}}

===[[cpp/coroutine|Coroutine support]]===
{{rrev|since=c++20|
Types for coroutine support, e.g. {{lc|std::coroutine_traits}}, {{lc|std::coroutine_handle}}.
}}

===[[cpp/utility/variadic|Variadic functions]]===
Support for functions that take an arbitrary number of parameters (via e.g. {{lc|va_start}}, {{lc|va_arg}}, {{lc|va_end}}).

==General-purpose utilities==
===Swap===
{{dsc begin}}
{{dsc header|utility}}
{{dsc inc|cpp/algorithm/dsc swap}}
{{dsc inc|cpp/utility/dsc exchange}}
{{dsc header|concepts}}
{{dsc inc|cpp/utility/ranges/dsc swap}}
{{dsc end}}

===Type operations===
{{dsc begin}}
{{dsc header|utility}}
{{dsc inc|cpp/utility/dsc forward}}
{{dsc inc|cpp/utility/dsc forward_like}}
{{dsc inc|cpp/utility/dsc move}}
{{dsc inc|cpp/utility/dsc move_if_noexcept}}
{{dsc inc|cpp/utility/dsc as_const}}
{{dsc inc|cpp/utility/dsc declval}}
{{dsc inc|cpp/utility/dsc to_underlying}}
{{dsc end}}

===Integer comparison functions===
{{dsc begin}}
{{dsc header|utility}}
{{dsc inc|cpp/utility/dsc intcmp}}
{{dsc inc|cpp/utility/dsc in_range}}
{{dsc end}}

===Relational operators===
{{dsc begin}}
{{dsc header|utility}}
{{dsc namespace|std::rel_ops}}
{{dsc inc|cpp/utility/rel_ops/dsc operator_cmp}}
{{dsc end}}

===Construction tags===
{{dsc begin}}
{{dsc header|utility}}
{{dsc inc|cpp/utility/dsc piecewise_construct}}
{{dsc inc|cpp/utility/dsc in_place}}
{{dsc inc|cpp/utility/dsc nontype}}
{{dsc end}}

===[[cpp/utility/pair|Pairs]] and [[cpp/utility/tuple|tuples]]===
{{dsc begin}}
{{dsc header|utility}}
{{dsc inc|cpp/utility/dsc pair}}
{{dsc header|tuple}}
{{dsc inc|cpp/utility/dsc tuple}}
{{dsc inc|cpp/utility/dsc apply}}
{{dsc inc|cpp/utility/dsc make_from_tuple}}
{{dsc h2|[[cpp/utility/tuple/tuple-like|Tuple protocol]]}}
{{dsc header|tuple}}
{{dsc header|utility}}
{{dsc header|array}}
{{dsc header|ranges}}
{{dsc header|complex}}
{{dsc inc|cpp/utility/dsc tuple_size}}
{{dsc inc|cpp/utility/dsc tuple_element}}
{{dsc end}}

===Sum types and type erased wrappers===
{{dsc begin}}
{{dsc header|optional}}
{{dsc inc|cpp/utility/dsc optional}}
{{dsc sep}}
{{dsc header|expected}}
{{dsc inc|cpp/utility/dsc expected}}
{{dsc sep}}
{{dsc header|variant}}
{{dsc inc|cpp/utility/dsc variant}}
{{dsc sep}}
{{dsc header|any}}
{{dsc inc|cpp/utility/dsc any}}
{{dsc end}}

===[[cpp/utility/bitset|Bitset]]===
{{dsc begin}}
{{dsc header|bitset}}
{{dsc inc|cpp/utility/dsc bitset}}
{{dsc end}}

===[[cpp/utility/functional|Function objects]]===
Partial function application (e.g. {{lc|std::bind}}) and related utilities: utilities for binding such as {{lc|std::ref}}  and {{lc|std::placeholders}}, polymorphic function wrappers: {{lc|std::function}}, predefined functors (e.g. {{lc|std::plus}}, {{lc|std::equal_to}}), pointer-to-member to function converters {{lc|std::mem_fn}}.

===[[cpp/utility/hash|Hash support]]===
{{dsc begin}}
{{dsc header|functional}}
{{dsc inc|cpp/utility/dsc hash}}
{{dsc end}}

===[[cpp/chrono|Date and time]]===
Time tracking (e.g. {{lc|std::chrono::time_point}}, {{lc|std::chrono::duration}}), C-style date and time (e.g. {{lc|std::time}}, {{lc|std::clock}})

===Primitive string conversions===
In addition to sophisticated locale-dependent parsers and formatters provided by the [[cpp/io|C++ I/O]] library, the [[cpp/io/c|C I/O]] library, [[cpp/string/basic_string#Numeric conversions|C++ string converters]], and [[cpp/string/byte#Conversions to numeric formats|C string converters]], the header {{header|charconv}} provides light-weight, locale-independent, non-allocating, non-throwing parsers and formatters for arithmetic types.
{{dsc begin}}
{{dsc header|charconv}}
{{dsc inc|cpp/utility/dsc to_chars}}
{{dsc inc|cpp/utility/dsc to_chars_result}}
{{dsc inc|cpp/utility/dsc from_chars}}
{{dsc inc|cpp/utility/dsc from_chars_result}}
{{dsc inc|cpp/utility/dsc chars_format}}
{{dsc end}}

===[[cpp/utility/format|Formatting library]]===
Facilities for type-safe string formatting.
{{dsc begin}}
{{dsc header|format}}
{{dsc inc|cpp/utility/format/dsc format}}
{{dsc inc|cpp/utility/format/dsc format_to}}
{{dsc inc|cpp/utility/format/dsc format_to_n}}
{{dsc inc|cpp/utility/format/dsc formatted_size}}
{{dsc inc|cpp/utility/format/dsc vformat}}
{{dsc inc|cpp/utility/format/dsc vformat_to}}
{{dsc inc|cpp/utility/format/dsc formatter}}
{{dsc inc|cpp/utility/format/dsc format_error}}
{{dsc end}}

===See also===
{{dsc begin}}
{{dsc see c|c/utility|Utility library|nomono=true}}
{{dsc end}}

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