From cppreference.com
Defined in header
voidunexpected();(until C++11)[[noreturn]]voidunexpected();(since C++11)
(until C++17)
(deprecated in C++11)std::unexpected() is called by the C++ runtime when a
dynamic exception specification
is violated: an exception is thrown from a function whose exception specification forbids exceptions of this type.
std::unexpected() may also be called directly from the program.
In either case, std::unexpected calls the currently installed
. The default
calls
.
If a destructor reset the unexpected handler during stack unwinding and the unwinding later led to unexpected being called, the handler that was installed at the end of the throw expression is the one that will be called (note: it was ambiguous whether re-throwing applied the new handlers).
(until C++11)If a destructor reset the unexpected handler during stack unwinding, it is unspecified which handler is called if the unwinding later led to unexpected being called.
(since C++11)Exceptions
Throw any exception thrown by the currently installed
.
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR Applied to Behavior as published Correct behavior
C++11 effect of calling
during stack
unwinding differs from C++98 and breaks some ABIs made unspecified See also