std::shared_ptr<T>::unique
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std::shared_ptr
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shared_ptr::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.
Contents
[edit] Parameters
(none)
[edit] Return value
true if *this is the only shared_ptr instance managing the current object, false otherwise.
[edit] 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 ).
[edit] 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