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std::unexpected_handler(3) C++ Standard Libary std::unexpected_handler(3)


std::unexpected_handler - std::unexpected_handler


Defined in header <exception>
typedef void (*unexpected_handler)(); (deprecated in C++11)
(removed in C++17)

std::unexpected_handler is the function pointer type (pointer to function that takes
no arguments and returns void), which is installed and queried by the functions
std::set_unexpected and std::get_unexpected and called by std::unexpected.

The C++ implementation provides a default std::unexpected_handler function, which
calls std::terminate(). If the null pointer value is installed (by means of
std::set_unexpected), the implementation may restore the default handler instead.

A user-defined std::unexpected_handler is expected to either terminate the program
or throw an exception. If it throws an exception, one of the following three
situations may be encountered:

1) the exception thrown by std::unexpected_handler satisfies the dynamic exception
specification that was violated earlier. The new exception is allowed to escape the
function and stack unwinding continues.

2) the exception thrown by std::unexpected_handler still violates the exception

2a) however, the exception specification allows std::bad_exception: the thrown
exception object is destroyed, and std::bad_exception is constructed by the C++
runtime and thrown instead.

2b) the exception specification does not allow std::bad_exception: std::terminate()
is called.

See also

unexpected function called when dynamic exception specification is
(removed in C++17) violated
set_unexpected changes the function to be called by std::unexpected
(removed in C++17) (function)
get_unexpected obtains the current unexpected_handler
(C++11)(removed in C++17) (function)