std::shared_ptr<T>::unique

 

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std::shared_ptr

成員函式

shared_ptr::shared_ptr

shared_ptr::~shared_ptr

shared_ptr::operator=

修改器

shared_ptr::reset

shared_ptr::swap

觀察器

shared_ptr::get

shared_ptr::operator*shared_ptr::operator->

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

shared_ptr::use_count

shared_ptr::unique (C++20之前已棄用，C++20中移除*)

shared_ptr::operator bool

shared_ptr::owner_before

shared_ptr::owner_hash (C++26)

shared_ptr::owner_equal (C++26)

非成員函式

swap(std::shared_ptr)

make_sharedmake_shared_for_overwrite (C++20 起)

allocate_sharedallocate_shared_for_overwrite (C++20 起)

static_pointer_castdynamic_pointer_castconst_pointer_castreinterpret_pointer_cast (C++17)

get_deleter

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

operator<<

atomic_xxx 函式 (C++20中已棄用，C++26中移除*)

輔助類

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

hash<std::shared_ptr>

推導指南(C++17)

 

bool unique() const noexcept;		(C++17 中已棄用) (C++20 中移除)

檢查 *this 是否是管理當前物件的唯一 shared_ptr 例項，即 use_count() == 1。

引數

(無)

返回值

如果 *this 是管理當前物件的唯一 shared_ptr 例項，則為 true，否則為 false。

注意

此函式在 C++17 中被棄用，並在 C++20 中被移除，因為在多執行緒環境中 use_count() == 1 是無意義的（參見 use_count 中的注意）。

示例

執行此程式碼

#include <iostream> 
#include <memory> 
 
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'; 
}

輸出

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

參閱

use_count

返回引用同一管理物件的 shared_ptr 物件的數量 (public member function)