Defined in header
Defines a type of object to be thrown as exception. It may be used to report arithmetic underflow errors (that is, situations where the result of a computation is a subnormal floating-point value)
The standard library components do not throw this exception (mathematical functions report underflow errors as specified in math_errhandling). Third-party libraries, however, use this. For example, boost.math throws
boost::math::policies::throw_on_error is enabled (the default setting).
 Member functions
| constructs the exception object |
(public member function)
explicit underflow_error( const std::string& what_arg );
explicit underflow_error( const char* what_arg );
Constructs the exception object with
what_arg as explanatory string that can be accessed through what().
std::exception is not permitted to throw exceptions, this message is typically stored internally as a copy-on-write string. This is also why there is no constructor taking
std::string&&: it would have to copy the content anyway.