nstructor will throw an exception of type bad_weak_ptr, and weak_ptr::lock will return an empty <a class="link" href="shared_ptr.html" title="Class template shared_ptr">shared_ptr</a>.</p>
<p>Every <a class="link" href="weak_ptr.html" title="Class template weak_ptr">weak_ptr</a> meets the CopyConstructible and Assignable requirements of the C++ Standard Library, and so can be used in standard library containers. Comparison operators are supplied so that <a class="link" href="weak_ptr.html" title="Class temp