std::is_member_pointer

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定义于头文件 <type_traits>
template< class T >
struct is_member_pointer;
(C++11 起)
T是指向非静态成员对象或一个非静态成员函数的指针,为会员提供恒定的value等于true。对于任何其他类型,valuefalse.
原文:
If T is pointer to non-static member object or a pointer to non-static member function, provides the member constant value equal true. For any other type, value is false.
这段文字是通过 Google Translate 自动翻译生成的。
您可以帮助我们检查、纠正翻译中的错误。详情请点击这里

目录

继承自 std::integral_constant

成员常量

value
[静态]
T is a member pointer type 则为true,否则为false
(公开静态成员常量)

成员函数

operator bool
转换对象为bool,返回value
(公开成员函数)
operator()
(C++14)
返回value
(公开成员函数)

成员类型

类型 定义
value_type bool
type std::integral_constant<bool, value>

[编辑] 可能的实现

template< class T >
struct is_member_pointer_helper         : std::false_type {};
 
template< class T, class U >
struct is_member_pointer_helper<T U::*> : std::true_type {};
 
template< class T >
struct is_member_pointer :
    is_member_pointer_helper<typename std::remove_cv<T>::type> {};

[编辑] 示例

#include <iostream>
#include <type_traits>
 
int main() {
    class cls {};
    std::cout << (std::is_member_pointer<int(cls::*)>::value
                     ? "T is member pointer"
                     : "T is not a member pointer") << '\n';
    std::cout << (std::is_member_pointer<int>::value
                     ? "T is member pointer"
                     : "T is not a member pointer") << '\n';
}

输出:

T is member pointer
T is not a member pointer

[编辑] 另请参阅

检查是否是指针类型
(类模板) [edit]
检查是否是一个指向非静态成员变量的指针类型
(类模板) [edit]
检查是否是指向非静态成员函数的指针类型
(类模板) [edit]