std::shared_ptr<T>::unique (3) - Linux Manuals

std::shared_ptr<T>::unique: std::shared_ptr<T>::unique

NAME

std::shared_ptr<T>::unique - std::shared_ptr<T>::unique

Synopsis

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