Dynamic memory management

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Utilities library

Language support Type support (basic types, RTTI) Library feature-test macros (C++20) Dynamic memory management Program utilities Coroutine support (C++20) Variadic functions is_constant_evaluated (C++20) is_within_lifetime (C++26) initializer_list (C++11) source_location (C++20) Three-way comparison three_way_comparablethree_way_comparable_with (C++20)(C++20) strong_ordering (C++20) weak_ordering (C++20) partial_ordering (C++20) common_comparison_category (C++20) compare_three_way_result (C++20) compare_three_way (C++20) strong_order (C++20) weak_order (C++20) partial_order (C++20) compare_strong_order_fallback (C++20) compare_weak_order_fallback (C++20) compare_partial_order_fallback (C++20)   is_eqis_ltis_lteq (C++20)(C++20)(C++20)   is_neqis_gtis_gteq (C++20)(C++20)(C++20)

General utilities Date and time Function objects Formatting library (C++20)   bitset hash (C++11) Relational operators (deprecated in C++20) rel_ops::operator!=rel_ops::operator>    rel_ops::operator<=rel_ops::operator>= Integer comparison functions cmp_equalcmp_lesscmp_less_than (C++20)(C++20)(C++20)   cmp_not_equalcmp_greatercmp_greater_than (C++20)(C++20)(C++20) in_range (C++20) Swap and type operations swap ranges::swap (C++20) exchange (C++14) declval (C++11) to_underlying (C++23) forward (C++11) forward_like (C++23) move (C++11) move_if_noexcept (C++11) as_const (C++17) Common vocabulary types pair tuple (C++11) optional (C++17) any (C++17) variant (C++17) tuple_size (C++11) tuple_element (C++11) apply (C++17) make_from_tuple (C++17) expected (C++23) Elementary string conversions to_chars (C++17) from_chars (C++17) chars_format (C++17) to_chars_result (C++17) from_chars_result (C++17)

 

Dynamic memory management

Uninitialized memory algorithms uninitialized_copy uninitialized_fill uninitialized_move (C++17) uninitialized_default_construct (C++17) uninitialized_value_construct (C++17) destroy (C++17) destroy_at (C++17) voidify (C++20) uninitialized_copy_n (C++11) uninitialized_fill_n uninitialized_move_n (C++17) uninitialized_default_construct_n (C++17) uninitialized_value_construct_n (C++17) destroy_n (C++17) construct_at (C++20) Constrained uninitialized memory algorithms ranges::uninitialized_copy (C++20) ranges::uninitialized_fill (C++20) ranges::uninitialized_move (C++20) ranges::construct_at (C++20) ranges::destroy (C++20) ranges::destroy_n (C++20) ranges::destroy_at (C++20) ranges::uninitialized_copy_n (C++20) ranges::uninitialized_fill_n (C++20) ranges::uninitialized_move_n (C++20) ranges::uninitialized_default_construct (C++20) ranges::uninitialized_value_construct (C++20) ranges::uninitialized_default_construct_n (C++20)   ranges::uninitialized_value_construct_n (C++20) Allocators allocator allocator_traits (C++11) allocation_result (C++23) allocator_arg (C++11) uses_allocator (C++11) uses_allocator_construction_args (C++20) make_obj_using_allocator (C++20) uninitialized_construct_using_allocator (C++20) scoped_allocator_adaptor (C++11) pmr::polymorphic_allocator (C++17) Memory resources pmr::memory_resource (C++17) pmr::get_default_resource (C++17) pmr::set_default_resource (C++17) pmr::new_delete_resource (C++17) pmr::null_memory_resource (C++17) pmr::synchronized_pool_resource (C++17) pmr::unsynchronized_pool_resource (C++17)   pmr::monotonic_buffer_resource (C++17) pmr::pool_options (C++17) Garbage collection support declare_reachable (C++11)(until C++23) undeclare_reachable (C++11)(until C++23) declare_no_pointers (C++11)(until C++23) undeclare_no_pointers (C++11)(until C++23) pointer_safety (C++11)(until C++23) get_pointer_safety (C++11)(until C++23) Uninitialized storage raw_storage_iterator (until C++20*) get_temporary_buffer (until C++20*) return_temporary_buffer (until C++20*) Explicit lifetime management start_lifetime_asstart_lifetime_as_array (C++23)(C++23)

Smart pointers unique_ptr (C++11) shared_ptr (C++11) weak_ptr (C++11) auto_ptr (until C++17*) owner_less (C++11) owner_less<void> (C++17) owner_hash (C++26) owner_equal (C++26) enable_shared_from_this (C++11) bad_weak_ptr (C++11) default_delete (C++11) out_ptr_t (C++23) inout_ptr_t (C++23) Low level memory management operator new operator new[] operator delete operator delete[] get_new_handler (C++11) set_new_handler launder (C++17) bad_alloc bad_array_new_length (C++11) nothrow_t align_val_t (C++17) destroying_delete_t (C++20) new_handler nothrow Miscellaneous pointer_traits (C++11) to_address (C++20) addressof (C++11) align (C++11) assume_aligned (C++20) C Library malloc calloc realloc    aligned_alloc (C++17) free

 

Smart pointers

Smart pointers enable automatic, exception-safe, object lifetime management.

Defined in header <memory>
Pointer categories
unique_ptr (C++11)	smart pointer with unique object ownership semantics (class template)
shared_ptr (C++11)	smart pointer with shared object ownership semantics (class template)
weak_ptr (C++11)	weak reference to an object managed by std::shared_ptr (class template)
auto_ptr (deprecated in C++11)(removed in C++17)	smart pointer with strict object ownership semantics (class template)
Helper classes
owner_less (C++11)	provides mixed-type owner-based ordering of shared and weak pointers (class template)
owner_hash (C++26)	provides owner-based hashing for shared and weak pointers (class)
owner_equal (C++26)	provides mixed-type owner-based equal comparisons of shared and weak pointers (class)
enable_shared_from_this (C++11)	allows an object to create a shared_ptr referring to itself (class template)
bad_weak_ptr (C++11)	exception thrown when accessing a weak_ptr which refers to already destroyed object (class)
default_delete (C++11)	default deleter for unique_ptr (class template)
Smart pointer adaptors
out_ptr_t (C++23)	interoperates with foreign pointer setters and resets a smart pointer on destruction (class template)
out_ptr (C++23)	creates an out_ptr_t with an associated smart pointer and resetting arguments (function template)
inout_ptr_t (C++23)	interoperates with foreign pointer setters, obtains the initial pointer value from a smart pointer, and resets it on destruction (class template)
inout_ptr (C++23)	creates an inout_ptr_t with an associated smart pointer and resetting arguments (function template)

Allocators

Allocators are class templates encapsulating memory allocation strategy. This allows generic containers to decouple memory management from the data itself.

Defined in header <memory>
allocator	the default allocator (class template)
allocator_traits (C++11)	provides information about allocator types (class template)
allocation_result (C++23)	records the address and the actual size of storage allocated by allocate_at_least (class template)
allocator_argallocator_arg_t (C++11)	a tag used to select allocator-aware constructors (tag)
uses_allocator (C++11)	checks if the specified type supports uses-allocator construction (class template)
uses_allocator_construction_args (C++20)	prepares the argument list matching the flavor of uses-allocator construction required by the given type (function template)
make_obj_using_allocator (C++20)	creates an object of the given type by means of uses-allocator construction (function template)
uninitialized_construct_using_allocator (C++20)	creates an object of the given type at specified memory location by means of uses-allocator construction (function template)
Defined in header <scoped_allocator>
scoped_allocator_adaptor (C++11)	implements multi-level allocator for multi-level containers (class template)
Defined in header <memory_resource>
Defined in namespace std::pmr
polymorphic_allocator (C++17)	an allocator that supports run-time polymorphism based on the std::pmr::memory_resource it is constructed with (class template)

Memory resources (since C++17)

Memory resources implement memory allocation strategies that can be used by std::pmr::polymorphic_allocator

Defined in header <memory_resource>
Defined in namespace std::pmr
memory_resource (C++17)	an abstract interface for classes that encapsulate memory resources (class)
new_delete_resource (C++17)	returns a static program-wide std::pmr::memory_resource that uses the global operator new and operator delete to allocate and deallocate memory (function)
null_memory_resource (C++17)	returns a static std::pmr::memory_resource that performs no allocation (function)
get_default_resource (C++17)	gets the default std::pmr::memory_resource (function)
set_default_resource (C++17)	sets the default std::pmr::memory_resource (function)
pool_options (C++17)	a set of constructor options for pool resources (class)
synchronized_pool_resource (C++17)	a thread-safe std::pmr::memory_resource for managing allocations in pools of different block sizes (class)
unsynchronized_pool_resource (C++17)	a thread-unsafe std::pmr::memory_resource for managing allocations in pools of different block sizes (class)
monotonic_buffer_resource (C++17)	a special-purpose std::pmr::memory_resource that releases the allocated memory only when the resource is destroyed (class)

Uninitialized storage

Several utilities are provided to create and access raw storage.

Defined in header <memory>
raw_storage_iterator (deprecated in C++17)(removed in C++20)	an iterator that allows standard algorithms to store results in uninitialized memory (class template)
get_temporary_buffer (deprecated in C++17)(removed in C++20)	obtains uninitialized storage (function template)
return_temporary_buffer (deprecated in C++17)(removed in C++20)	frees uninitialized storage (function template)

Uninitialized memory algorithms

Defined in header <memory>
uninitialized_copy	copies a range of objects to an uninitialized area of memory (function template)
uninitialized_copy_n (C++11)	copies a number of objects to an uninitialized area of memory (function template)
uninitialized_fill	copies an object to an uninitialized area of memory, defined by a range (function template)
uninitialized_fill_n	copies an object to an uninitialized area of memory, defined by a start and a count (function template)
uninitialized_move (C++17)	moves a range of objects to an uninitialized area of memory (function template)
uninitialized_move_n (C++17)	moves a number of objects to an uninitialized area of memory (function template)
uninitialized_default_construct (C++17)	constructs objects by default-initialization in an uninitialized area of memory, defined by a range (function template)
uninitialized_default_construct_n (C++17)	constructs objects by default-initialization in an uninitialized area of memory, defined by a start and a count (function template)
uninitialized_value_construct (C++17)	constructs objects by value-initialization in an uninitialized area of memory, defined by a range (function template)
uninitialized_value_construct_n (C++17)	constructs objects by value-initialization in an uninitialized area of memory, defined by a start and a count (function template)
destroy_at (C++17)	destroys an object at a given address (function template)
destroy (C++17)	destroys a range of objects (function template)
destroy_n (C++17)	destroys a number of objects in a range (function template)
construct_at (C++20)	creates an object at a given address (function template)

Constrained uninitialized memory algorithms (since C++20)

C++20 provides constrained uninitialized memory algorithms that accept range arguments or iterator-sentinel pairs.

Defined in header <memory>
Defined in namespace std::ranges
no-throw-input-iteratorno-throw-forward-iteratorno-throw-sentinel-forno-throw-input-rangeno-throw-forward-range (C++20)	specifies some operations on iterators, sentinels and ranges are non-throwing (exposition-only concept*)
ranges::uninitialized_copy (C++20)	copies a range of objects to an uninitialized area of memory (niebloid)
ranges::uninitialized_copy_n (C++20)	copies a number of objects to an uninitialized area of memory (niebloid)
ranges::uninitialized_fill (C++20)	copies an object to an uninitialized area of memory, defined by a range (niebloid)
ranges::uninitialized_fill_n (C++20)	copies an object to an uninitialized area of memory, defined by a start and a count (niebloid)
ranges::uninitialized_move (C++20)	moves a range of objects to an uninitialized area of memory (niebloid)
ranges::uninitialized_move_n (C++20)	moves a number of objects to an uninitialized area of memory (niebloid)
ranges::uninitialized_default_construct (C++20)	constructs objects by default-initialization in an uninitialized area of memory, defined by a range (niebloid)
ranges::uninitialized_default_construct_n (C++20)	constructs objects by default-initialization in an uninitialized area of memory, defined by a start and count (niebloid)
ranges::uninitialized_value_construct (C++20)	constructs objects by value-initialization in an uninitialized area of memory, defined by a range (niebloid)
ranges::uninitialized_value_construct_n (C++20)	constructs objects by value-initialization in an uninitialized area of memory, defined by a start and a count (niebloid)
ranges::destroy_at (C++20)	destroys an object at a given address (niebloid)
ranges::destroy (C++20)	destroys a range of objects (niebloid)
ranges::destroy_n (C++20)	destroys a number of objects in a range (niebloid)
ranges::construct_at (C++20)	creates an object at a given address (niebloid)

Garbage collector support (until C++23)

Defined in header <memory>
declare_reachable (C++11)(removed in C++23)	declares that an object can not be recycled (function)
undeclare_reachable (C++11)(removed in C++23)	declares that an object can be recycled (function template)
declare_no_pointers (C++11)(removed in C++23)	declares that a memory area does not contain traceable pointers (function)
undeclare_no_pointers (C++11)(removed in C++23)	cancels the effect of std::declare_no_pointers (function)
pointer_safety (C++11)(removed in C++23)	lists pointer safety models (enum)
get_pointer_safety (C++11)(removed in C++23)	returns the current pointer safety model (function)

Explicit lifetime management (since C++23)

Defined in header <memory>
start_lifetime_asstart_lifetime_as_array (C++23)	implicitly creates objects in given storage with the object representation reused (function template)

Miscellaneous

Defined in header <memory>
pointer_traits (C++11)	provides information about pointer-like types (class template)
to_address (C++20)	obtains a raw pointer from a pointer-like type (function template)
addressof (C++11)	obtains actual address of an object, even if the & operator is overloaded (function template)
align (C++11)	aligns a pointer in a buffer (function)
assume_aligned (C++20)	informs the compiler that a pointer is aligned (function template)

Low level memory management

Includes e.g. operator new, operator delete, std::set_new_handler

Defined in header <new>

C-style memory management

Includes e.g. std::malloc, std::free

Defined in header <cstdlib>