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std::underflow_error

Defined in header <stdexcept>
class underflow_error;

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 std::underflow_error if boost::math::policies::throw_on_error is enabled (the default setting).

cpp/error/exception cpp/error/runtime errorstd-underflow error-inheritance.svg

Inheritance diagram.

Member functions

(constructor)
constructs the exception object
(public member function)

std::underflow_error::underflow_error

explicit underflow_error( const std::string& what_arg );
(1)
explicit underflow_error( const char* what_arg );
(2) (since C++11)

Constructs the exception object with what_arg as explanatory string that can be accessed through what().

Because copying std::underflow_error is not permitted to throw exceptions, this message is typically stored internally as a separately-allocated reference-counted string. This is also why there is no constructor taking std::string&&: it would have to copy the content anyway.

Parameters

what_arg - explanatory string

Exceptions

May throw std::bad_alloc.

Inherited from std::exception

Member functions

[virtual]
destroys the exception object
(virtual public member function of std::exception)
[virtual]
returns an explanatory string
(virtual public member function of std::exception)

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