std:: stack

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

The std::stack class is a container adaptor that gives the programmer the functionality of a stack - 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.

Template parameters

T	-	The type of the stored elements. The program is ill-formed if T is not the same type as Container::value_type .
Container	-	The type of the underlying container to use to store the elements. The container must satisfy the requirements of SequenceContainer . Additionally, it must provide the following functions with the usual 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 containers std::vector (including std::vector<bool> ), std::deque and std::list satisfy these requirements. By default, if no container class is specified for a particular stack class instantiation, the standard container std::deque is used.

Member types

Type	Definition
container_type	Container
value_type	Container::value_type
size_type	Container :: size_type
reference	Container::reference
const_reference	Container::const_reference

Member objects

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

Member functions

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

Non-member functions

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

Helper classes

std::uses_allocator <std::stack> (C++11)	specializes the std::uses_allocator type trait (class template specialization)
std::formatter <std::stack> (C++23)	formatting support for std::stack (class template specialization)

Deduction guides

(since C++17)

Notes

Feature-test macro	Value	Std	Feature
__cpp_lib_containers_ranges	202202L	(C++23)	Ranges construction and insertion for containers

Example

This section is incomplete Reason: no example

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

See also

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