std::weak_ptr::expired

 

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weak_ptr::use_count

weak_ptr::expired

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std::swap

 

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.

Run this code

#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

See also

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)