NAME¶

std::range_error - std::range_error

Synopsis¶

Defined in header <stdexcept>
class range_error;

Defines a type of object to be thrown as exception. It can be used to report range
errors (that is, situations where a result of a computation cannot be represented by
the destination type).

The only standard library components that throw this exception are
std::wstring_convert::from_bytes and std::wstring_convert::to_bytes.

The mathematical functions in the standard library components do not throw this
exception (mathematical functions report range errors as specified in
math_errhandling).

std-range error-inheritance.svg

Inheritance diagram

Member functions¶

constructor constructs a new range_error object with the given message
(public member function)
operator= replaces the range_error object
(public member function)

std::range_error::range_error

range_error( const std::string& what_arg ); (1)
range_error( const char* what_arg ); (2)
range_error( const range_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::range_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::range_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.

Before the resolution of LWG issue 254, the non-copy constructor can only accept
std::string. It makes dynamic allocation mandatory in order to construct 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::range_error::operator=

range_error& operator=( const range_error& other ); (noexcept since C++11)

Assigns the contents with those of other. If *this and other both have dynamic type
std::range_error then std::strcmp(what(), other.what()) == 0 after 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 retroactively to
previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 254 C++98 the constructor accepting const char* added
was missing
the explanatory strings of they are the same as that
LWG 471 C++98 std::range_error's of the
copies were implementation-defined original std::range_error
object