std::is_standard_layout

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C++
 
实用工具库
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日期和时间
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initializer_list（C++11）
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hash（C++11）
关系运算符
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Relational operators
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rel_ops::operator!=
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Pairs and tuples
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pair
tuple（C++11）
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piecewise_construct（C++11）
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Swap, forward and move
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swap
forward（C++11）
move（C++11）
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declval（C++11）
 
类型的支持
基本类型
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Basic types
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基本类型
固定宽度的整数类型 （C++11）
nullptr_t（C++11）
offsetof
NULL
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Numeric limits
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C数字限制接口
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Type traits
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is_standard_layout（C++11）
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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）
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（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）
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Relationships and property queries
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remove_const
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add_const
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add_lvalue_reference
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类型转换
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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）
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_standard_layout;
 （C++11 起）
T是一个标准的布局类型（即标量类型，一个标准布局类，或者一个数组的类型/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 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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一个标准布局类是一个类
Original:
A standard-layout class is a class that
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1。有没有非静态数据成员不是标准布局
Original:
1. has no non-static data members that aren't standard-layout
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2。没有虚函数，和无虚基类的
Original:
2. has no virtual functions and no virtual base classes
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3。所有非静态数据成员具有相同的访问控制
Original:
3. has the same access control for all non-static data members
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4。没有基类的标准布局
Original:
4. has no base classes that aren't standard-layout
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5。或者没有基类的非静态数据成员，或有没有非静态数据成员中最派生类，其中只有一个基地
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。有没有基类的相同类型的第一个非静态数据成员
Original:
6. has no base classes of the same type as the first non-static data member
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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 standard-layout type ，false其他方式
Original:
true if T is a standard-layout 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

一个标准布局类的指针可以转换与reinterpret_cast的一个指针，指向第一个非静态数据成员，反之亦然.
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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如果的标准布局工会的持有两个或两个以上标准的布局结构，它允许检查的一部分，他们共同的初始.
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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宏offsetof只能用于与标准布局类.
Original:
The macro offsetof can only be used with standard-layout classes.
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[编辑] 为例

#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';
}

Output: 

true
false
false

[编辑] 另请参阅

（C++11）
 checks if a type is trivially copyable
（类模板） [edit]
（C++11）
检查如果一个类型是普通的旧数据（POD）类型
Original:
checks if a type is plain-old data (POD) type
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（类模板） [edit]
一个标准的布局类型指定的成员从一开始的字节偏移量
Original:
byte offset from the beginning of a standard-layout type to specified member
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（函数宏） [edit]
来自“http://zh.cppreference.com/mwiki/index.php?title=cpp/types/is_standard_layout&oldid=27294”