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std::is_abstract

提供: cppreference.com
< cpp‎ | types

 
 
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
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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
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Swap, forward and move
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swap
forward(C++11)
move(C++11)
move_if_noexcept(C++11)
declval(C++11)
 
支援を入力します
基本的なタイプ
Original:
Basic types
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基本的なタイプ
固定幅の整数型 (C++11)
数値の限界
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Numeric limits
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numeric_limits
Cの数値は、インターフェイスを制限します
実行時型情報
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Runtime type information
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型の特徴
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Type traits
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プライマリタイプカテゴリ
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Primary type categories
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is_void(C++11)
is_array(C++11)
is_pointer(C++11)
is_enum(C++11)
is_union(C++11)
is_class(C++11)
is_function(C++11)
is_object(C++11)
is_scalar(C++11)
is_compound(C++11)
is_integral(C++11)
is_floating_point(C++11)
is_fundamental(C++11)
is_arithmetic(C++11)
is_reference(C++11)
is_lvalue_reference(C++11)
is_rvalue_reference(C++11)
is_member_pointer(C++11)
is_member_object_pointer(C++11)
is_member_function_pointer(C++11)
Typeプロパティ
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Type properties
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is_const(C++11)
is_volatile(C++11)
is_pod(C++11)
is_empty(C++11)
is_polymorphic(C++11)
is_abstract(C++11)
サポートされる操作
Original:
Supported operations
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is_constructible
is_trivially_constructible
is_nothrow_constructible
(C++11)
(C++11)
(C++11)
is_default_constructible
is_trivially_default_constructible
is_nothrow_default_constructible
(C++11)
(C++11)
(C++11)
is_copy_constructible
is_trivially_copy_constructible
is_nothrow_copy_constructible
(C++11)
(C++11)
(C++11)
is_move_constructible
is_trivially_move_constructible
is_nothrow_move_constructible
(C++11)
(C++11)
(C++11)
is_assignable
is_trivially_assignable
is_nothrow_assignable
(C++11)
(C++11)
(C++11)
is_copy_assignable
is_trivially_copy_assignable
is_nothrow_copy_assignable
(C++11)
(C++11)
(C++11)
is_move_assignable
is_trivially_move_assignable
is_nothrow_move_assignable
(C++11)
(C++11)
(C++11)
is_destructible
is_trivially_destructible
is_nothrow_destructible
(C++11)
(C++11)
(C++11)
has_virtual_destructor(C++11)
リレーションシップとプロパティクエリ
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Relationships and property queries
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is_same(C++11)
is_base_of(C++11)
is_convertible(C++11)
alignment_of(C++11)
rank(C++11)
extent(C++11)
型の変更
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Type modifications
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remove_cv
remove_const
remove_volatile
(C++11)
(C++11)
(C++11)
add_cv
add_const
add_volatile
(C++11)
(C++11)
(C++11)
make_signed(C++11)
make_unsigned(C++11)
型変換
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Type transformations
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aligned_storage(C++11)
aligned_union(C++11)
decay(C++11)
enable_if(C++11)
conditional(C++11)
common_type(C++11)
underlying_type(C++11)
result_of(C++11)
形質定数を入力します
Original:
Type trait constants
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integral_constant(C++11)
 
Defined in header <type_traits>
template< class T >
struct is_abstract;
(C + + 11以来)
Tは抽象クラス(少なくとも1つの純粋仮想関数を宣言または継承したクラスである)である場合、メンバーが一定提供value等しいtrueを。その他のタイプのために、valuefalseです.
Original:
If T is an abstract class (that is, a class that declares or inherits at least one pure virtual function), provides the member constant value equal true. For any other type, value is false.
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目次

Inherited from std::integral_constant

Member constants

value
[静的]
true T is an abstract class type もし、そうでなければfalse
Original:
true if T is an abstract class type , false otherwise
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(公共の静的メンバ定数)

Member functions

operator bool
boolにオブジェクトは、value返しに変換します
Original:
converts the object to bool, 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 bool
type std::integral_constant<bool, value>

[編集] ノート

抽象クラスは、基本クラスとして使用されるかもしれません。抽象クラス型のないオブジェクトは、基本クラスのサブオブジェクトの形を除いて作成することができません.
Original:
Abstract classes may only be used as base classes; no objects of an abstract class type can be created except in form of base class subobjects.
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純粋仮想関数が純粋なものではない仮想関数をオーバーライドする場合、抽象クラスは抽象クラスでないクラスから派生することができる.
Original:
An abstract class may be derived from a class that is not abstract if a pure virtual function overrides a virtual function that is not pure.
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[編集]

#include <iostream>
#include <type_traits>
 
struct A {
    int m;
};
 
struct B {
    virtual void foo();
};
 
struct C {
    virtual void foo() = 0;
};
 
struct D : C {};
 
int main()
{
    std::cout << std::boolalpha;
    std::cout << std::is_abstract<A>::value << '\n';
    std::cout << std::is_abstract<B>::value << '\n';
    std::cout << std::is_abstract<C>::value << '\n';
    std::cout << std::is_abstract<D>::value << '\n';
}

Output:

false
false
true
true

[編集] も参照してください

(C++11)
checks if a type is a class type (but not union type)
(クラステンプレート) [edit]
タイプかどうかをチェックし、ポリモーフィッククラス型です
Original:
checks if a type is polymorphic class type
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(クラステンプレート) [edit]