std::weak_ptr::expired
From cppreference.com
| bool expired() const noexcept; |
(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).
Contents |
[edit] Parameters
(none)
[edit] Return value
true if the managed object has already been deleted, false otherwise.
[edit] Notes
This function is inherently racy if the managed object is shared among threads. In particular, a false result may become stale before it can be used. A true result is reliable.
[edit] 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
[edit] See also
creates a shared_ptr that manages the referenced object (public member function) | |
returns the number of shared_ptr objects that manage the object (public member function) |
