Utility library

C++ includes a variety of utility libraries that provide functionality ranging from bit-counting to partial function application. These libraries can be broadly divided into two groups:

language support libraries, and
general-purpose libraries.

[edit] Language support

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

[edit] Type support

Basic types (e.g. std::size_t, std::nullptr_t), RTTI (e.g. std::type_info), type traits (e.g. std::is_integral, std::rank)

[edit] Dynamic memory management

Smart pointers (e.g. std::shared_ptr), allocators (e.g. std::allocator or std::memory_resource), C-style memory management (e.g. std::malloc)

[edit] Error handling

Exceptions (e.g. std::exception, std::logic_error), assertions (e.g. assert)

[edit] Initializer lists

initializer_list

(C++11)

allows the use of initializer list syntax to initialize non-aggregate types
(class template)

[edit] Variadic functions

Support for functions that take an arbitrary number of parameters (via e.g. va_start, va_arg, va_end)

[edit] General-purpose utilities

[edit] Program utilities

Termination (e.g. std::abort, std::atexit), environment (e.g. std::system), signals (e.g. std::raise)

[edit] Date and time

Time tracking (e.g. std::chrono::time_point, std::chrono::duration), C-style date and time (e.g. std::time, std::clock)

[edit] Bitset

bitset

implements constant length bit array
(class)

Partial function application (e.g. std::bind) and related utilities: utilities for binding such as std::ref and std::placeholders, polymorphic function wrappers: std::function, predefined functors (e.g. std::plus, std::equal_to), method to function converters std::mem_fn.

[edit] std::optional

Class template representing a value that may or may not be present.

[edit] std::any

A type-safe container for single values of any type.

[edit] Pairs and tuples

pair	implements binary tuple, i.e. a pair of values (class template)
tuple (C++11)	implements fixed size container, which holds elements of possibly different types (class template)
apply (C++17)	calls a function with a tuple of arguments (function template)
piecewise_construct_t (C++11)	tag type used to select correct function overload for piecewise construction (class)
piecewise_construct (C++11)	an object of type `piecewise_construct_t` used to disambiguate functions for piecewise construction (constant)
integer_sequence (C++14)	implements compile-time sequence of integers (class template)

[edit] Swap, forward and move

swap	swaps the values of two objects (function template)
exchange (C++14)	replaces the argument with a new value and returns its previous value (function template)
forward (C++11)	forwards a function argument (function template)
move (C++11)	obtains an rvalue reference (function template)
move_if_noexcept (C++11)	obtains an rvalue reference if the move constructor does not throw (function template)

[edit] Type operations

declval (C++11)	obtains a reference to its argument for use in unevaluated context (function template)
as_const (C++17)	obtains a reference to const to its argument (function template)

[edit] Relational operators

Defined in namespace `std::rel_ops`
operator!=operator>operator<=operator>=	automatically generates comparison operators based on user-defined operator== and operator< (function template)

[edit] Hash support

hash