std::shared_ptr<T>::unique

 

C++

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std::shared_ptr

成员函数

shared_ptr::shared_ptr

shared_ptr::~shared_ptr

shared_ptr::operator=

修改器

shared_ptr::reset

shared_ptr::swap

观察器

shared_ptr::get

shared_ptr::operator*shared_ptr::operator->

shared_ptr::operator[] (C++17)

shared_ptr::use_count

shared_ptr::unique (C++20 前)

shared_ptr::operator bool

shared_ptr::owner_before

非成员函数

std::swap

make_sharedmake_shared_for_overwrite (C++20)

allocate_sharedallocate_shared_for_overwrite (C++20)

static_pointer_castdynamic_pointer_castconst_pointer_castreinterpret_pointer_cast (C++17)

get_deleter

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

operator<<

atomic_ 函数(C++20 中弃用)

辅助类

std::atomic<std::shared_ptr> (C++20)

std::hash

推导指引(C++17)

 

bool unique() const noexcept;		(C++17 中弃用) (C++20 中移除)

检查 *this 是否管理当前对象的仅有 shared_ptr 实例，即是否 use_count() == 1 。

参数

（无）

返回值

若 *this 否管理当前对象的仅有 shared_ptr 实例则为 true ，否则为 false 。

注意

此函数于 C++17 中被弃用并于 C++20 中移除，因为 use_count 在多线程环境中只是估计（见 use_count 中的“注意”）。

示例

运行此代码

#include <memory> 
#include <iostream> 
 
int main() 
{ 
    auto sp1 = std::make_shared<int>(5);
    std::cout << std::boolalpha;
    std::cout << "sp1.unique() == " << sp1.unique() << '\n'; 
 
    std::shared_ptr<int> sp2 = sp1; 
    std::cout << "sp1.unique() == " << sp1.unique() << '\n'; 
}

输出：

sp1.unique() == true
sp1.unique() == false

参阅

use_count

返回 shared_ptr 所指对象的引用计数 (公开成员函数)