std:: pair
|
Defined in header
<utility>
|
||
|
template
<
class
T1,
|
||
std::pair
is a class template that provides a way to store two heterogeneous objects as a single unit. A pair is a specific case of a
std::tuple
with two elements.
If neither
T1
nor
T2
is a possibly cv-qualified class type with non-trivial destructor, or array thereof, the destructor of
pair
is trivial.
Template parameters
| T1, T2 | - | the types of the elements that the pair stores. |
Member types
| Member type | Definition |
first_type
|
T1
|
second_type
|
T2
|
Member objects
| Member name | Type |
first
|
T1
|
second
|
T2
|
Member functions
constructs new
pair
(public member function) |
|
|
assigns the contents
(public member function) |
|
|
(C++11)
|
swaps the contents
(public member function) |
Non-member functions
creates a
pair
object of type, determined by the argument types
(function template) |
|
|
(removed in C++20)
(removed in C++20)
(removed in C++20)
(removed in C++20)
(removed in C++20)
(C++20)
|
lexicographically compares the values in the
pair
(function template) |
|
(C++11)
|
specializes the
std::swap
algorithm
(function template) |
|
(C++11)
|
accesses an element of a
pair
(function template) |
Helper classes
|
(C++11)
|
obtains the size of a
pair
(class template specialization) |
|
(C++11)
|
obtains the type of the elements of
pair
(class template specialization) |
determines the common reference type of two
pair
s
(class template specialization) |
|
|
(C++23)
|
determines the common type of two
pair
s
(class template specialization) |
|
(C++23)
|
formatting support for
pair
(class template specialization) |
Helper specializations
|
template
<
class
T,
class
U
>
constexpr
bool
enable_nonlocking_formatter_optimization
<
std
::
pair
<
T, U
>>
|
(since C++23) | |
This specialization of
std::enable_nonlocking_formatter_optimization
enables efficient implementation of
std::print
and
std::println
for printing a
pair
object when both
T
and
U
enable it.
Deduction guides (since C++17)
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 2796 | C++98 |
triviality of the destructor of
pair
was unspecified
|
specified |
See also
|
(C++11)
|
implements fixed size container, which holds elements of possibly different types
(class template) |
|
(C++11)
|
creates a
tuple
of lvalue references or unpacks a tuple into individual objects
(function template) |