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# std::shared_ptr::unique

From cppreference.com
< cpp‎ | memory‎ | shared ptr

bool unique() const noexcept; |  | (deprecated)

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

### [edit] Parameters

(none)

### [edit] Return value

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

### [edit] Exceptions

`noexcept` specification:
noexcept

### [edit] Notes

This function is deprecated as of C++17 because use_count is only an approximation in multithreaded environment.

### [edit] 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

### [edit] See also

use_count | returns the number of `shared_ptr` objects referring to the same managed object (public member function) [edit]

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