std::weak_ptr::expired

1	`bool` `expired()` `const;`

(since C++11)

Checks whether the managed object has already been deleted. Equivalent to use_count() == 0.

Parameters

(none).

Return value

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

Exceptions

noexcept specification:

noexcept

Example

Demonstrates how expired is used to check validity of the pointer.

#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();
}

Output:

gw is valid
gw is expired

lock	creates a `shared_ptr` that manages the referenced object (public member function)
use_count	returns the number of `shared_ptr` objects that manage the object (public member function)

std::weak_ptr::expired

Parameters

Return value

Exceptions

Example

See also