std::stack

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std::stack

Member functions
stack::stack
stack::~stack
stack::operator=
Element access
stack::top
Capacity
stack::empty
stack::size
Modifiers
stack::push
stack::push_range (C++23)
stack::emplace (C++11)
stack::pop
stack::swap (C++11)
Non-member functions
swap(std::stack) (C++11)
operator==operator!=operator<operator>operator<=operator>=operator<=> (C++20)
Helper classes
uses_allocator<std::stack> (C++11)
formatter<std::stack> (C++23)
Deduction guides(C++17)

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Defined in header`<stack>`
template< class T, class Container=std::deque<T> >class stack;

Thestd::stack class is acontainer adaptor that gives the programmer the functionality of astack - specifically, a LIFO (last-in, first-out) data structure.

The class template acts as a wrapper to the underlying container - only a specific set of functions is provided. The stack pushes and pops the element from the back of the underlying container, known as the top of the stack.

All member functions ofstd::stack areconstexpr: it is possible to create and usestd::stack objects in the evaluation of a constant expression.

However,std::stack objects generally cannot beconstexpr, because any dynamically allocated storage must be released in the same evaluation of constant expression.

(since C++26)

[edit]Template parameters

T - The type of the stored elements. The program is ill-formed ifT is not the same type asContainer::value_type.

Container

The type of the underlying container to use to store the elements. The container must satisfy the requirements ofSequenceContainer. Additionally, it must provide the following functions with theusual semantics:

back(), e.g.,std::vector::back(),
push_back(), e.g.,std::deque::push_back(),
pop_back(), e.g.,std::list::pop_back().

The standard containersstd::vector (includingstd::vector<bool>),std::deque andstd::list satisfy these requirements. By default, if no container class is specified for a particular stack class instantiation, the standard containerstd::deque is used.

[edit]Member types

Type	Definition
`container_type`	`Container`[edit]
`value_type`	`Container::value_type`[edit]
`size_type`	Container::size_type[edit]
`reference`	`Container::reference`[edit]
`const_reference`	`Container::const_reference`[edit]

[edit]Member objects

Member	Description
Container c	the underlying container (protected member object)[edit]

[edit]Member functions

(constructor)	constructs the`stack` (public member function)[edit]
(destructor)	destructs the`stack` (public member function)[edit]
operator=	assigns values to the container adaptor (public member function)[edit]
Element access
top	accesses the top element (public member function)[edit]
Capacity
empty	checks whether the container adaptor is empty (public member function)[edit]
size	returns the number of elements (public member function)[edit]
Modifiers
push	inserts element at the top (public member function)[edit]
push_range (C++23)	inserts a range of elements at the top (public member function)[edit]
emplace (C++11)	constructs element in-place at the top (public member function)[edit]
pop	removes the top element (public member function)[edit]
swap (C++11)	swaps the contents (public member function)[edit]

[edit]Non-member functions

operator==operator!=operator<operator<=operator>operator>=operator<=> (C++20)	lexicographically compares the values of two`stack`s (function template)[edit]
std::swap(std::stack) (C++11)	specializes thestd::swap algorithm (function template)[edit]

[edit]Helper classes

std::uses_allocator<std::stack> (C++11)	specializes thestd::uses_allocator type trait (class template specialization)[edit]
std::formatter<std::stack> (C++23)	formatting support for`std::stack` (class template specialization)[edit]

Deduction guides

(since C++17)

[edit]Notes

Feature-test macro	Value	Std	Feature
`__cpp_lib_containers_ranges`	`202202L`	(C++23)	Ranges construction and insertion for containers
`__cpp_lib_constexpr_stack`	`202502L`	(C++26)	constexpr`std::stack`

[edit]Example

This section is incomplete
Reason: no example

[edit]Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 307	C++98	`Container` could not be`std::vector<bool>`	allowed
LWG 2566	C++98	Missing the requirement for`Container::value_type`	ill-formed if`T` is not the same type as`Container::value_type`

[edit]See also

vector	resizable contiguous array (class template)[edit]
vector<bool>	space-efficient dynamic bitset (class template specialization)[edit]
deque	double-ended queue (class template)[edit]
list	doubly-linked list (class template)[edit]