std::shared_ptr<T>::unique
Declarations
Deprecated in C++17, Removed in C++20
bool unique() const noexcept;
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
#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';
}
Possible Result
sp1.unique() == true
sp1.unique() == false