std::shared_ptr<T>::unique

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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

Notes

This function was deprecated in C++17 and removed in C++20 because use_count() == 1 is meaningless in multithreaded environment (see Notes in use_count

Example

Run this code
#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'; 
}

Output: 

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

See also

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