std::is_unsigned

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C++
 
实用工具库
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类型的支持
基本类型
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Basic types
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is_unsigned（C++11）
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is_constructible
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is_move_constructible
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is_assignable
is_trivially_assignable
is_nothrow_assignable		（C++11）
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is_copy_assignable
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is_nothrow_copy_assignable		（C++11）
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is_move_assignable
is_trivially_move_assignable
is_nothrow_move_assignable		（C++11）
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is_destructible
is_trivially_destructible
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键入特征常数
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Type trait constants
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integral_constant（C++11）
 
Defined in header <type_traits>
template< class T >
struct is_unsigned;
 （C++11 起）
T是一个无符号的算术类型，提供成员value等于true。对于任何其他类型，value是false.
Original:
If T is an unsigned arithmetic type, provides the member constant value equal true. For any other type, value is false.
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目录

Inherited from std::integral_constant

Member constants

value
[静态的] </ SPAN></div></div>
true如果 T is an unsigned arithmetic type ，false其他方式
Original:
true if T is an unsigned arithmetic type , false otherwise
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（公共静态成员常量）

Member functions

operator bool
转换的对象bool，返回value
Original:
converts the object to bool, returns value
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（公共成员函数）

Member types

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

</div>

[编辑] 为例

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

Output: 

false
false
false
true
false
false

[编辑] 另请参阅

（C++11）
检查
Original:
checks if a type is signed arithmetic type
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（类模板） [edit]
（C++11）
检查如果一个类型是浮点型
Original:
checks if a type is floating-point type
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（类模板） [edit]
（C++11）
检查如果一个类型是整数类型
Original:
checks if a type is integral type
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（类模板） [edit]
（C++11）
整体式签署
Original:
makes the given integral type signed
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（类模板） [edit]
（C++11）
整体式无符号
Original:
makes the given integral type unsigned
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（类模板） [edit]
来自“http://zh.cppreference.com/mwiki/index.php?title=cpp/types/is_unsigned&oldid=27260”