std::weak_ptr<T>::expired

Since C++11

Equivalent to use_count() == 0. The destructor for the managed object may not yet have been called, but this object’s destruction is imminent (or may have already happened).

# Declarations

bool expired() const noexcept;

(since C++11)

# Return value

true if the managed object has already been deleted, false otherwise.

# Notes

If the managed object is shared among threads, it is only meaningful when expired() returns true.

# Example

#include <iostream>
#include <memory>
 
std::weak_ptr<int> gw;
 
void f()
{
    if (!gw.expired())
	std::cout << "gw is valid\n";
    else
        std::cout << "gw is expired\n";
}
 
int main()
{
    {
        auto sp = std::make_shared<int>(42);
	gw = sp;
 
	f();
    }
 
    f();
}

# See also