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std::is_standard_layout

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C++
 
Утилиты библиотеки
 
Поддержка типов
Основные типы
Original:
Basic types
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Основные типы
Исправлены типы целых ширину (C++11)
Числовые пределы
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Numeric limits
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numeric_limits
С числовым ограничивает интерфейс
Время тип информации
Original:
Runtime type information
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Тип черты
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Type traits
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Первичные категории типа
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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)
Тип свойства
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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)
is_trivial(C++11)
is_trivially_copyable(C++11)
is_standard_layout(C++11)
is_literal_type(C++11)
is_signed(C++11)
is_unsigned(C++11)
Поддерживаемые операции
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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)
Отношения собственности и запросов
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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)
Тип модификаций
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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)
Тип преобразования
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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)
Введите черта констант
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Type trait constants
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integral_constant(C++11)
 
Заголовочный файл <type_traits>
template< class T >
struct is_standard_layout;
 (начиная с C++11)
Если T является стандартным типом раскладки (т. е. скалярный тип, стандарт-класса макета, или массив такого типа / класса, возможно, резюме квалифицированных), обеспечивает постоянный член value равных true. Для любого другого типа, value является false.
Original:
If T is a standard layout type (that is, a scalar type, a standard-layout class, or an array of such type/class, possibly cv-qualified), provides the member constant value equal true. For any other type, value is false.
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Стандартная раскладка-класс это класс, который
Original:
A standard-layout class is a class that
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1. не имеет не статические данные пользователей, которые не являются стандартными-макета
Original:
1. has no non-static data members that aren't standard-layout
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2. не имеет виртуальные функции и не виртуальных базовых классов
Original:
2. has no virtual functions and no virtual base classes
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3. имеет такой же контроль доступа для всех не-статических данных-членов
Original:
3. has the same access control for all non-static data members
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4. не имеет базовых классов, которые не являются стандартными-макета
Original:
4. has no base classes that aren't standard-layout
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5. либо не имеет базового класса с не статические данные члены или не имеет не статические данные члены в наиболее производный класс и только одна база с ними
Original:
5. either has no base class with non-static data members or has no non-static data members in the most derived class and only one base with them
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6. не имеет базовые классы одного и того же типа, что и первый не-статический член данных
Original:
6. has no base classes of the same type as the first non-static data member
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Содержание

Унаследован от std::integral_constant

Member constants

value
[static]
true если T is a standard-layout type , false иначе
Original:
true if T is a standard-layout type , false otherwise
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(public static константа-член)

Member functions

operator bool
преобразует объект в bool, возвращает value
Original:
converts the object to bool, returns value
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(public функция-член)

Member types

Type
Original:
Type
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 Definition
value_type bool
type std::integral_constant<bool, value>

[править] Notes

Указатель на стандартных макетов классов могут быть конвертированы (с reinterpret_cast) к указателю на свой первый не статические данные члены и наоборот.
Original:
A pointer to a standard-layout class may be converted (with reinterpret_cast) to a pointer to its first non-static data member and vice versa.
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Если стандарт-макет союз имеет два или более стандартных макетов структуры, он имеет право инспектировать общую начальную часть из них.
Original:
If a standard-layout union holds two or more standard-layout structs, it is permitted to inspect the common initial part of them.
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Макрос offsetof могут быть использованы только со стандартным макетом классов.
Original:
The macro offsetof can only be used with standard-layout classes.
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[править] Пример

#include <iostream>
#include <type_traits>
 
struct A {
    int m;
};
 
struct B {
    int m1;
private:
    int m2;
};
 
struct C {
    virtual void foo();
};
 
int main()
{
    std::cout << std::boolalpha;
    std::cout << std::is_standard_layout<A>::value << '\n';
    std::cout << std::is_standard_layout<B>::value << '\n';
    std::cout << std::is_standard_layout<C>::value << '\n';
}

Вывод: 

true
false
false

[править] См. также

(C++11)
 checks if a type is trivially copyable
(шаблон класса) [edit]
(C++11)
проверяет, является ли тип обычный старый данных (POD) типа
Original:
checks if a type is plain-old data (POD) type
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(шаблон класса) [edit]
байтовое смещение от начала стандартной верстки типа указанного члена
Original:
byte offset from the beginning of a standard-layout type to specified member
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(функция-макрос) [edit]
Источник — «http://ru.cppreference.com/mwiki/index.php?title=cpp/types/is_standard_layout&oldid=28226»