std::bad_weak_ptr
Defined in header <memory>
class bad_weak_ptr;
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
exception <- bad_weak_ptr
Member functions
pub | (constructor) | constructs a new bad_weak_ptr object (public member function) |
pub | operator= | replaces the bad_weak_ptr object (public member function) |
pub | what | returns the explanatory string (public member function) |
std::bad_weak_ptr::bad_weak_ptr
bad_weak_ptr() noexcept; (1)
bad_weak_ptr( const bad_weak_ptr& other ) noexcept; (2)
Constructs a new bad_weak_ptr object with an implementation-defined null-terminated byte string which is accessible through what()
.
- Default constructor.
- Copy constructor. If
*this
and other both have dynamic type std::bad_weak_ptr thenstd::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;
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;
Returns the explanatory string.
Parameters
(none)
Return value
Pointer to a 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.
Notes
Implementations are allowed but not required to override what()
.
Inherited from std::exception
Member functions
pub | (destructor) [virtual] | destroys the exception object (virtual public member function of std::exception) |
pub | what [virtual] | returns an explanatory string (virtual public member function of std::exception) |
Example
#include <memory>
#include <iostream>
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';
}
}
std::bad_weak_ptr
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
LWG 2376 | C++11 | calling what on a default-constructed bad_weak_ptr was required to return "bad_weak_ptr" | the return value is implementation-defined |