operator==,!=,<,<=,>,>=,<=>(std::unique_ptr)

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std::unique_ptr

成员函数

unique_ptr::unique_ptr

unique_ptr::~unique_ptr

unique_ptr::operator=

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unique_ptr::release

unique_ptr::reset

unique_ptr::swap

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unique_ptr::get

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unique_ptr::operator bool

unique_ptr::operator*unique_ptr::operator->

unique_ptr::operator[]

非成员函数

make_uniquemake_unique_for_overwrite (C++14)(C++20)

operator==operator!=operator<operator>operator<=operator>=operator<=> (C++20 前)(C++20)

operator<< (C++20)

swap(std::unique_ptr)

辅助类

hash<std::unique_ptr>

 

<tbody> </tbody>

在标头 <memory> 定义
template< class T1, class D1, class T2, class D2 > bool operator==( const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y );	(1)	(C++11 起) (constexpr since C++23)
template< class T1, class D1, class T2, class D2 > bool operator!=( const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y );	(2)	(C++11 起) (C++20 前)
template< class T1, class D1, class T2, class D2 > bool operator<( const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y );	(3)	(C++11 起)
template< class T1, class D1, class T2, class D2 > bool operator<=( const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y );	(4)	(C++11 起)
template< class T1, class D1, class T2, class D2 > bool operator>( const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y );	(5)	(C++11 起)
template< class T1, class D1, class T2, class D2 > bool operator>=( const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y );	(6)	(C++11 起)
template< class T1, class D1, class T2, class D2 > requires std::three_way_comparable_with< typename unique_ptr<T1, D1>::pointer, typename unique_ptr<T2, D2>::pointer> std::compare_three_way_result_t<typename unique_ptr<T1, D1>::pointer, typename unique_ptr<T2, D2>::pointer> operator<=>( const unique_ptr<T1, D1>& x, const unique_ptr<T2, D2>& y );	(7)	(C++20 起)
template< class T, class D > bool operator==( const unique_ptr<T, D>& x, std::nullptr_t ) noexcept;	(8)	(C++11 起) (constexpr since C++23)
template< class T, class D > bool operator==( std::nullptr_t, const unique_ptr<T, D>& x ) noexcept;	(9)	(C++11 起) (C++20 前)
template< class T, class D > bool operator!=( const unique_ptr<T, D>& x, std::nullptr_t ) noexcept;	(10)	(C++11 起) (C++20 前)
template< class T, class D > bool operator!=( std::nullptr_t, const unique_ptr<T, D>& x ) noexcept;	(11)	(C++11 起) (C++20 前)
template< class T, class D > bool operator<( const unique_ptr<T, D>& x, std::nullptr_t );	(12)	(C++11 起) (constexpr since C++23)
template< class T, class D > bool operator<( std::nullptr_t, const unique_ptr<T, D>& y );	(13)	(C++11 起) (constexpr since C++23)
template< class T, class D > bool operator<=( const unique_ptr<T, D>& x, std::nullptr_t );	(14)	(C++11 起) (constexpr since C++23)
template< class T, class D > bool operator<=( std::nullptr_t, const unique_ptr<T, D>& y );	(15)	(C++11 起) (constexpr since C++23)
template< class T, class D > bool operator>( const unique_ptr<T, D>& x, std::nullptr_t );	(16)	(C++11 起) (constexpr since C++23)
template< class T, class D > bool operator>( std::nullptr_t, const unique_ptr<T, D>& y );	(17)	(C++11 起) (constexpr since C++23)
template< class T, class D > bool operator>=( const unique_ptr<T, D>& x, std::nullptr_t );	(18)	(C++11 起) (constexpr since C++23)
template< class T, class D > bool operator>=( std::nullptr_t, const unique_ptr<T, D>& y );	(19)	(C++11 起) (constexpr since C++23)
template< class T, class D > requires std::three_way_comparable<typename unique_ptr<T, D>::pointer> std::compare_three_way_result_t<typename unique_ptr<T, D>::pointer> operator<=>( const unique_ptr<T, D>& x, std::nullptr_t );	(20)	(C++20 起) (constexpr since C++23)

比较两个 unique_ptr 或 unique_ptr 与 nullptr 的指针值。

1-7) 比较两个 unique_ptr。

8-20) 比较 unique_ptr 与 nullptr。

!= 运算符从 operator== 运算符合成。

(C++20 起)

参数

x, y

-

要比较的 unique_ptr

返回值

1) x.get() == y.get()

2) x.get() != y.get()

3) std::less<CT>()(x.get(), y.get())，其中 CT 是 std::common_type<unique_ptr<T1, D1>::pointer, unique_ptr<T2, D2>::pointer>::type

4) !(y < x)

5) y < x

6) !(x < y)

7) std::compare_three_way{}(x.get(), y.get())

8,9) !x

10,11) (bool)x

12) std::less<unique_ptr<T,D>::pointer>()(x.get(), nullptr)

13) std::less<unique_ptr<T,D>::pointer>()(nullptr, y.get())

14) !(nullptr < x)

15) !(y < nullptr)

16) nullptr < x

17) y < nullptr

18) !(x < nullptr)

19) !(nullptr < y)

20) std::compare_three_way{}(x.get(), static_cast<typename unique_ptr<T, D>::pointer>(nullptr))

示例

运行此代码

#include <iostream>
#include <memory>

int main()
{
    std::unique_ptr<int> p1(new int(42));
    std::unique_ptr<int> p2(new int(42));

    std::cout << std::boolalpha
        << "(p1 == p1)       : " << (p1 == p1) << '\n'
        << "(p1 <=> p1) == 0 : " << ((p1 <=> p1) == 0) << '\n' // C++20 起

    // p1 与 p2 指向不同内存位置，故 p1 != p2
        << "(p1 == p2)       : " << (p1 == p2) << '\n'
        << "(p1 < p2)        : " << (p1 < p2) << '\n'
        << "(p1 <=> p2) < 0  : " << ((p1 <=> p2) < 0) << '\n'   // C++20 起
        << "(p1 <=> p2) == 0 : " << ((p1 <=> p2) == 0) << '\n'; // C++20 起
}

可能的输出：

(p1 == p1)       : true
(p1 <=> p1) == 0 : true
(p1 == p2)       : false
(p1 < p2)        : true
(p1 <=> p2) < 0  : true
(p1 <=> p2) == 0 : false

缺陷报告

下列更改行为的缺陷报告追溯地应用于以前出版的 C++ 标准。

缺陷报告	应用于	出版时的行为	正确行为
LWG 3426	C++20	operator<=>(unique_ptr, nullptr_t) 非良构	修正约束与定义

参阅

get	返回指向被管理对象的指针 (公开成员函数)