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std::tuple_size<std::tuple>

提供: cppreference.com
< cpp‎ | utility‎ | tuple

 
 
ユーティリティライブラリ
支援を入力します (basic types, RTTI, type traits)
動的なメモリ管理
エラー処理
プログラムユーティリティ
可変個引数関数
日付と時刻
関数オブジェクト
initializer_list(C++11)
bitset
hash(C++11)
関係演算子
Original:
Relational operators
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rel_ops::operator!=
rel_ops::operator>
rel_ops::operator<=
rel_ops::operator>=
ペアとタプル
Original:
Pairs and tuples
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pair
tuple(C++11)
piecewise_construct_t(C++11)
piecewise_construct(C++11)
フォワード、スワップ、および移動
Original:
Swap, forward and move
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swap
forward(C++11)
move(C++11)
move_if_noexcept(C++11)
declval(C++11)
 
std::tuple
メンバ関数
Original:
Member functions
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tuple::tuple
tuple::operator=
tuple::swap
非メンバ関数
Original:
Non-member functions
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make_tuple
tie
forward_as_tuple
None
operator=
operator!=
operator<
operator<=
operator>
operator>=
std::swap
get
ヘルパークラス
Original:
Helper classes
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tuple_size
tuple_element
uses_allocator
ignore
 
Defined in header <tuple>
template< class T >
class tuple_size; /*undefined*/
(1) (C + + 11以来)
template< class... Types >

class tuple_size<tuple<Types...> >

 : public std::integral_constant<std::size_t, sizeof...(Types)> { };
(2) (C + + 11以来)
template< class T >

class tuple_size<const T>
 : public std::integral_constant<
             typename std::remove_cv<decltype(std::tuple_size<T>::value)>::type,

             std::tuple_size<Tp>::value> { };
(3) (C + + 11以来)
template< class T >

class tuple_size< volatile T >
 : public std::integral_constant<
             typename std::remove_cv<decltype(std::tuple_size<T>::value)>::type,

             std::tuple_size<Tp>::value> { };
(4) (C + + 11以来)
template< class T >

class tuple_size< const volatile T >
 : public std::integral_constant<
             typename std::remove_cv<decltype(std::tuple_size<T>::value)>::type,

             std::tuple_size<Tp>::value> { };
(5) (C + + 11以来)
コンパイル時の定数式としてタプル内の要素数へのアクセスを提供します.
Original:
Provides access to the number of elements in a tuple as a compile-time constant expression.
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目次

Inherited from std::integral_constant

Member constants

value
[静的]
sizeof...(Types)
(公共の静的メンバ定数)

Member functions

operator std::size_t
std::size_tにオブジェクトは、value返しに変換します
Original:
converts the object to std::size_t, returns value
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(パブリックメンバ関数)

Member types

タイプ
Original:
Type
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Definition
value_type std::size_t
type std::integral_constant<std::size_t, value>

[編集]

#include <iostream>
#include <tuple>
 
template<class T>
void test(T t)
{
    int a[std::tuple_size<T>::value]; // can be used at compile time
    std::cout << std::tuple_size<T>::value << '\n'; // or at run time
}
 
int main()
{
    test(std::make_tuple(1, 2, 3.14));
}

Output:

3

[編集] も参照してください

arrayのサイズを取得します
Original:
obtains the size of an array
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(クラステンプレートの特殊化の2つの値を比較します) [edit]
pairのサイズを取得します
Original:
obtains the size of a pair
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(クラステンプレートの特殊化の2つの値を比較します) [edit]
タプルは、指定された要素にアクセスします
Original:
tuple accesses specified element
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(関数テンプレート) [edit]
指定された要素の型を取得します
Original:
obtains the type of the specified element
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(クラステンプレートの特殊化の2つの値を比較します) [edit]