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std::is_signed

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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
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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_signed;
 (начиная с C++11)
Если T является подписанный арифметического типа, обеспечивает постоянный член value равных true. Для любого другого типа, value является false.
Original:
If T is a signed arithmetic type, provides the member constant value equal true. For any other type, value is false.
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Содержание

Унаследован от std::integral_constant

Member constants

value
[static]
true если T is a signed arithmetic type , false иначе
Original:
true if T is a signed arithmetic 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] Пример

#include <iostream>
#include <type_traits>
 
class A {};
enum B : int {};
enum class C : int {};
 
int main()
{
    std::cout << std::boolalpha;
    std::cout << std::is_signed<A>::value << '\n';
    std::cout << std::is_signed<float>::value << '\n';
    std::cout << std::is_signed<signed int>::value << '\n';
    std::cout << std::is_signed<unsigned int>::value << '\n';
    std::cout << std::is_signed<B>::value << '\n';
    std::cout << std::is_signed<C>::value << '\n';
}

Вывод: 

false
true
true
false
false
false

[править] См. также

(C++11)
проверяет, является ли тип без знака арифметического типа
Original:
checks if a type is unsigned arithmetic type
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(шаблон класса) [edit]
[static]
определяет подписан типов
Original:
identifies signed types
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(public static константа-член std::numeric_limits) [edit]
(C++11)
проверяет, является ли тип с плавающей запятой
Original:
checks if a type is floating-point type
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(шаблон класса) [edit]
(C++11)
проверяет, является ли тип интегрального типа
Original:
checks if a type is integral type
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(шаблон класса) [edit]
(C++11)
делает данный интегрального типа подписано
Original:
makes the given integral type signed
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(шаблон класса) [edit]
(C++11)
делает данный интегральный тип без знака
Original:
makes the given integral type unsigned
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(шаблон класса) [edit]
Источник — «http://ru.cppreference.com/mwiki/index.php?title=cpp/types/is_signed&oldid=28236»