std::shared_ptr<T>::unique

 

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std::shared_ptr

Member functions

shared_ptr::shared_ptr

shared_ptr::~shared_ptr

shared_ptr::operator=

Modifiers

shared_ptr::reset

shared_ptr::swap

Observers

shared_ptr::get

shared_ptr::operator*shared_ptr::operator->

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

shared_ptr::use_count

shared_ptr::unique (until C++20)

shared_ptr::operator bool

shared_ptr::owner_before

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std::swap

make_sharedmake_shared_for_overwrite (C++20)

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static_pointer_castdynamic_pointer_castconst_pointer_castreinterpret_pointer_cast (C++17)

get_deleter

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operator<<

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

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bool unique() const noexcept;		(deprecated in C++17) (removed in C++20)

Checks if *this is the only shared_ptr instance managing the current object, i.e. whether use_count() == 1.

Parameters

(none)

Return value

true if *this is the only shared_ptr instance managing the current object, false otherwise.

Notes

This function was deprecated in C++17 and removed in C++20 because use_count is only an approximation in multithreaded environment (see Notes in use_count).

Example

Run this code

#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'; 
}

Output:

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

See also

use_count

returns the number of shared_ptr objects referring to the same managed object (public member function)