FreeBSD Manual Pages
std::underflow_error(3) C++ Standard Libary std::underflow_error(3) NAME std::underflow_error - std::underflow_error Synopsis 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 (mathe- matical functions report underflow errors as specified in math_errhandling). Third- party libraries, however, use this. For example, boost.math throws std::underflow_er- ror if boost::math::policies::throw_on_error is enabled (the default set- ting). std-underflow error-inheritance.svg Inheritance diagram Member functions constructor constructs a new underflow_error object with the given message (public member function) operator= replaces the underflow_error object (public member function) std::underflow_error::underflow_error underflow_error( const std::string& what_arg ); (1) underflow_error( const char* what_arg ); (2) underflow_error( const underflow_error& other ); (3) (noexcept since C++11) 1) Constructs the exception object with what_arg as explanatory string. After construction, std::strcmp(what(), what_arg.c_str()) == 0. 2) Constructs the exception object with what_arg as explanatory string. After construction, std::strcmp(what(), what_arg) == 0. 3) Copy constructor. If *this and other both have dynamic type std::underflow_error then std::strcmp(what(), other.what()) == 0. No exception can be thrown from the copy constructor. Parameters what_arg - explanatory string other - another exception object to copy Exceptions 1,2) May throw std::bad_alloc. Notes Because copying std::underflow_error is not permitted to throw ex- ceptions, 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. Before the resolution of LWG issue 254, the non-copy constructor can only accept std::string. It makes dynamic allocation mandatory in order to con- struct a std::string object. After the resolution of LWG issue 471, a derived standard exception class must have a publicly accessible copy constructor. It can be implicitly defined as long as the explanatory strings obtained by what() are the same for the original object and the copied object. std::underflow_error::operator= underflow_error& operator=( const underflow_error& other ); (noex- cept since C++11) Assigns the contents with those of other. If *this and other both have dynamic type std::underflow_error then std::strcmp(what(), other.what()) == 0 af- ter assignment. No exception can be thrown from the copy assignment operator. Parameters other - another exception object to assign with Return value *this Notes After the resolution of LWG issue 471, a derived standard exception class must have a publicly accessible copy assignment operator. It can be implicitly defined as long as the explanatory strings obtained by what() are the same for the original object and the copied object. Inherited from std::runtime_error Inherited from std::exception Member functions destructor destroys the exception object [virtual] (virtual public member function of std::exception) what returns an explanatory string [virtual] (virtual public member function of std::exception) Defect reports The following behavior-changing defect reports were applied retroac- tively to previously published C++ standards. DR Applied to Behavior as published Correct behavior LWG 254 C++98 the constructor accepting const added char* was missing the explanatory strings of they are the same as that of LWG 471 C++98 std::underflow_error's the copies were implementation-defined original std::underflow_error object http://cppreference.com 2024.06.10 std::underflow_error(3)
NAME | Synopsis | Member functions | Parameters | Exceptions | Notes | Parameters | Return value | Notes | Member functions
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=std::underflow_error&sektion=3&manpath=FreeBSD+Ports+15.1.quarterly>