std::get(std::pair) - cppreference.com (original) (raw)
| Defined in header | ||
|---|---|---|
| template< std::size_t I, class T1, class T2 > typename std::tuple_element<I, std::pair<T1,T2> >::type& get( std::pair<T1, T2>& p ) noexcept; | (1) | (since C++11) (constexpr since C++14) |
| template< std::size_t I, class T1, class T2 > const typename std::tuple_element<I, std::pair<T1,T2> >::type& get( const std::pair<T1,T2>& p ) noexcept; | (2) | (since C++11) (constexpr since C++14) |
| template< std::size_t I, class T1, class T2 > typename std::tuple_element<I, std::pair<T1,T2> >::type&& get( std::pair<T1,T2>&& p ) noexcept; | (3) | (since C++11) (constexpr since C++14) |
| template< std::size_t I, class T1, class T2 > const typename std::tuple_element<I, std::pair<T1,T2> >::type&& get( const std::pair<T1,T2>&& p ) noexcept; | (4) | (since C++11) (constexpr since C++14) |
| template< class T, class U > constexpr T& get( std::pair<T, U>& p ) noexcept; | (5) | (since C++14) |
| template< class T, class U > constexpr const T& get( const std::pair<T, U>& p ) noexcept; | (6) | (since C++14) |
| template< class T, class U > constexpr T&& get( std::pair<T, U>&& p ) noexcept; | (7) | (since C++14) |
| template< class T, class U > constexpr const T&& get( const std::pair<T, U>&& p ) noexcept; | (8) | (since C++14) |
| template< class T, class U > constexpr T& get( std::pair<U, T>& p ) noexcept; | (9) | (since C++14) |
| template< class T, class U > constexpr const T& get( const std::pair<U, T>& p ) noexcept; | (10) | (since C++14) |
| template< class T, class U > constexpr T&& get( std::pair<U, T>&& p ) noexcept; | (11) | (since C++14) |
| template< class T, class U > constexpr const T&& get( const std::pair<U, T>&& p ) noexcept; | (12) | (since C++14) |
Extracts an element from the pair using tuple-like interface.
1-4) The index-based overloads fail to compile if the index I is neither 0 nor 1.
5-12) The type-based overloads fail to compile if the types T and U are the same.
[edit] Parameters
| p | - | pair whose contents to extract |
|---|
[edit] Return value
1-4) Returns a reference to p.first if I == 0 and a reference to p.second if I == 1.
5-8) Returns a reference to p.first.
9-12) Returns a reference to p.second.
[edit] Example
#include #include int main() { auto p = std::make_pair(1, 3.14); std::cout << '(' << std::get<0>(p) << ", " << std::get<1>(p) << ")\n"; std::cout << '(' << std::get(p) << ", " << std::get(p) << ")\n"; }
Output:
[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 2485 | C++11 (by index)C++14 (by type) | there are no overloads for const pair&& | the overloads are added |
[edit] See also
| Structured binding (C++17) | binds the specified names to sub-objects or tuple elements of the initializer[edit] |
|---|---|
| get(std::tuple)(C++11) | tuple accesses specified element (function template) [edit] |
| get(std::array)(C++11) | accesses an element of an array (function template) [edit] |
| get(std::variant)(C++17) | reads the value of the variant given the index or the type (if the type is unique), throws on error (function template) [edit] |
| get(std::ranges::subrange)(C++20) | obtains iterator or sentinel from a std::ranges::subrange (function template) [edit] |
| get(std::complex)(C++26) | obtains a reference to real or imaginary part from a std::complex (function template) [edit] |