std::bad_weak_ptr
Defined in header <memory>
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class bad_weak_ptr; |
(since C++11) | |
std::bad_weak_ptr
is the type of the object thrown as exceptions by the constructors of std::shared_ptr that take std::weak_ptr as the argument, when the std::weak_ptr refers to an already deleted object.
Inheritance diagram
Contents |
[edit] Member functions
(constructor) |
constructs a new bad_weak_ptr object (public member function) |
operator= |
replaces the bad_weak_ptr object (public member function) |
what |
returns the explanatory string (public member function) |
std::bad_weak_ptr::bad_weak_ptr
bad_weak_ptr() noexcept; |
(1) | (since C++11) |
bad_weak_ptr( const bad_weak_ptr& other ) noexcept; |
(2) | (since C++11) |
Constructs a new bad_weak_ptr
object with an implementation-defined null-terminated byte string which is accessible through what().
std::bad_weak_ptr
then std::strcmp(what(), other.what()) == 0.Parameters
other | - | another exception object to copy |
std::bad_weak_ptr::operator=
bad_weak_ptr& operator=( const bad_weak_ptr& other ) noexcept; |
(since C++11) | |
Assigns the contents with those of other.If *this and other both have dynamic type std::bad_weak_ptr
then std::strcmp(what(), other.what()) == 0 after assignment.
Parameters
other | - | another exception object to assign with |
Return value
*this
std::bad_weak_ptr::what
virtual const char* what() const noexcept; |
(since C++11) | |
Returns the explanatory string.
Return value
Pointer to an implementation-defined null-terminated string with explanatory information. The string is suitable for conversion and display as a std::wstring. The pointer is guaranteed to be valid at least until the exception object from which it is obtained is destroyed, or until a non-const member function (e.g. copy assignment operator) on the exception object is called.
The returned string is encoded with the ordinary literal encoding during constant evaluation. |
(since C++26) |
Notes
Implementations are allowed but not required to override what()
.
Inherited from std::exception
Member functions
[virtual] |
destroys the exception object (virtual public member function of std::exception )
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[virtual] |
returns an explanatory string (virtual public member function of std::exception )
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[edit] Example
#include <iostream> #include <memory> int main() { std::shared_ptr<int> p1(new int(42)); std::weak_ptr<int> wp(p1); p1.reset(); try { std::shared_ptr<int> p2(wp); } catch (const std::bad_weak_ptr& e) { std::cout << e.what() << '\n'; } }
Possible output:
std::bad_weak_ptr
[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
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LWG 2376 | C++11 | calling what on a default-constructed bad_weak_ptr was required to return "bad_weak_ptr"
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the return value is implementation-defined |
[edit] See also
(C++11) |
smart pointer with shared object ownership semantics (class template) |
(C++11) |
weak reference to an object managed by std::shared_ptr (class template) |