std::is_trivial

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C++
 
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类型的支持
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is_constructible
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is_trivially_move_constructible
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is_assignable
is_trivially_assignable
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is_copy_assignable
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is_move_assignable
is_trivially_move_assignable
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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_trivial;
 （C++11 起）
T是一个简单的类型（即标量类型，一个平凡复制的一个平凡的默认构造函数的类，或数组类型/类，可能CV合格的），提供会员value等于true。对于任何其他类型，value是false.
Original:
If T is a trivial type (that is, a scalar type, a trivially copyable class with a trivial default constructor, or 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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目录

Inherited from std::integral_constant

Member constants

value
[静态的] </ SPAN></div></div>
true如果 T is a trivial type ，false其他方式
Original:
true if T is a trivial 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] 注释

唯一的对象（包括数组），就可以创建简单的类型调用std::malloc.
Original:
Only objects (including arrays) of trivial type may be created by a call to std::malloc.
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[编辑] 可能的实现

template< class T >
struct is_trivial : std::integral_constant<
    bool,
    std::is_trivially_copyable<T>::value &&
    std::is_trivially_default_constructible<T>::value
> {};

[编辑] 为例

#include <iostream>
#include <type_traits>
 
struct A {
    int m;
};
 
struct B {
    B() {}
};
 
int main()
{
    std::cout << std::boolalpha;
    std::cout << std::is_trivial<A>::value << '\n';
    std::cout << std::is_trivial<B>::value << '\n';
}

Output: 

true
false

[编辑] 另请参阅

（C++11）
 checks if a type is trivially copyable
（类模板） [edit]
来自“http://zh.cppreference.com/mwiki/index.php?title=cpp/types/is_trivial&oldid=27284”