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Difference between revisions of "cpp/container/stack"

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< cpp‎ | container
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}}
 
}}
  
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The {{tt|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.
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The {{tt|std::stack}} class is a [[cpp/container#Container adaptors|container adaptor]] that gives the programmer the functionality of a {{enwiki|Stack (abstract data type)|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.
 
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.
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===Template parameters===
 
===Template parameters===
 
{{par begin}}
 
{{par begin}}
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{{par|T|The type of the stored elements. The behavior is undefined if {{tt|T}} is not the same type as {{tt|Container::value_type}}.<!-- LWG2566 -->}}
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{{par|T|The type of the stored elements. The program is ill-formed if {{tt|T}} is not the same type as {{tt|Container::value_type}}.}}
−
{{par|Container|The type of the underlying container to use to store the elements. The container must satisfy the requirements of {{named req|SequenceContainer}}. Additionally, it must provide the following functions with the usual semantics:
+
{{par|Container|The type of the underlying container to use to store the elements. The container must satisfy the requirements of {{named req|SequenceContainer}}. Additionally, it must provide the following functions with the [[cpp/named req/SequenceContainer#Optional operations|usual semantics]]:
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* {{tt|back()}}
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* {{tt|back()}}, e.g., {{lc|std::vector::back()}},
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* {{tt|push_back()}}
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* {{tt|push_back()}}, e.g., {{lc|std::deque::push_back()}},
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* {{tt|pop_back()}}
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* {{tt|pop_back()}}, e.g., {{lc|std::list::pop_back()}}.
  
 
The standard containers {{lc|std::vector}} (including {{ltt|cpp/container/vector_bool|std::vector<bool>}}), {{lc|std::deque}} and {{lc|std::list}} satisfy these requirements.  By default, if no container class is specified for a particular stack class instantiation, the standard container {{lc|std::deque}} is used.
 
The standard containers {{lc|std::vector}} (including {{ltt|cpp/container/vector_bool|std::vector<bool>}}), {{lc|std::deque}} and {{lc|std::list}} satisfy these requirements.  By default, if no container class is specified for a particular stack class instantiation, the standard container {{lc|std::deque}} is used.
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===Member types===
 
===Member types===
 
{{dsc begin}}
 
{{dsc begin}}
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{{dsc hitem|Member type|Definition}}
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{{dsc hitem|Type|Definition}}
 
{{dsc inc|cpp/container/dsc container_type|stack}}
 
{{dsc inc|cpp/container/dsc container_type|stack}}
 
{{dsc inc|cpp/container/dsc value_type|stack}}
 
{{dsc inc|cpp/container/dsc value_type|stack}}
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{{dsc inc|cpp/container/dsc reference|stack}}
 
{{dsc inc|cpp/container/dsc reference|stack}}
 
{{dsc inc|cpp/container/dsc const_reference|stack}}
 
{{dsc inc|cpp/container/dsc const_reference|stack}}
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{{dsc end}}
 +
 +
===Member objects===
 +
{{dsc begin}}
 +
{{dsc hitem|Member|Description}}
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{{dsc inc|cpp/container/dsc c|stack}}
 
{{dsc end}}
 
{{dsc end}}
  
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{{dsc h2|Modifiers}}
 
{{dsc h2|Modifiers}}
 
{{dsc inc|cpp/container/dsc push|stack}}
 
{{dsc inc|cpp/container/dsc push|stack}}
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{{dsc inc|cpp/container/dsc emplace|stack}}
 
 
{{dsc inc|cpp/container/dsc push_range|stack}}
 
{{dsc inc|cpp/container/dsc push_range|stack}}
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{{dsc inc|cpp/container/dsc emplace|stack}}
 
{{dsc inc|cpp/container/dsc pop|stack}}
 
{{dsc inc|cpp/container/dsc pop|stack}}
 
{{dsc inc|cpp/container/dsc swap|stack}}
 
{{dsc inc|cpp/container/dsc swap|stack}}
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{{dsc h1|Member objects}}
 
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{{dsc inc|cpp/container/dsc c|stack}}
 
 
{{dsc end}}
 
{{dsc end}}
  
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{{dsc begin}}
 
{{dsc begin}}
 
{{dsc inc|cpp/container/dsc uses_allocator|stack}}
 
{{dsc inc|cpp/container/dsc uses_allocator|stack}}
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{{dsc inc|cpp/container/dsc adaptor_formatter|stack}}
 
{{dsc end}}
 
{{dsc end}}
  
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{{rrev|noborder=true|since=c++17|{{=}}{{=}}{{=}}{{rl|deduction guides|Deduction guides}}{{=}}{{=}}{{=}}}}
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{{rrev|since=c++17|
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==={{rl|deduction guides|Deduction guides}}===
 +
}}
  
 
===Notes===
 
===Notes===
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{{dr list begin}}
 
{{dr list begin}}
 
{{dr list item|wg=lwg|dr=307|std=C++98|before={{tt|Container}} could not be {{tt|std::vector<bool>}}|after=allowed}}
 
{{dr list item|wg=lwg|dr=307|std=C++98|before={{tt|Container}} could not be {{tt|std::vector<bool>}}|after=allowed}}
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{{dr list item|wg=lwg|dr=2566|std=C++98|before=Missing the requirement for {{tt|Container::value_type}} |after=ill-formed if {{tt|T}} is not the same type as {{tt|Container::value_type}}}}
 
{{dr list end}}
 
{{dr list end}}
  

Latest revision as of 15:41, 1 November 2024

 
C++
 
Containers library
 
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.

Contents

[edit] 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:

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.

[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

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

[edit] Non-member functions

(C++20)
 lexicographically compares the values of two stacks
(function template) [edit]
(C++11)
 specializes the std::swap algorithm
(function template) [edit]

[edit] Helper classes

(C++11)
 specializes the std::uses_allocator type trait
(class template specialization) [edit]
(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

[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

 dynamic contiguous array
(class template) [edit]
space-efficient dynamic bitset
(class template specialization) [edit]
double-ended queue
(class template) [edit]
doubly-linked list
(class template) [edit]
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