NAME

std::runtime_error - std::runtime_error

Synopsis

Defined in header <stdexcept>
class runtime_error;

Defines a type of object to be thrown as exception. It reports errors that are due
to events beyond the scope of the program and can not be easily predicted.

Exceptions of type std::runtime_error are thrown by the following standard library
components: std::locale::locale and std::locale::combine.

In addition, the following standard exception types are derived from
std::runtime_error:

* std::range_error
* std::overflow_error
* std::underflow_error

* std::regex_error (since C++11)
* std::system_error

* std::chrono::ambiguous_local_time
* std::chrono::nonexistent_local_time (since C++20)
* std::format_error

std-runtime error-inheritance.svg

Inheritance diagram

Member functions

constructor constructs a new runtime_error object with the given message
(public member function)
operator= replaces the runtime_error object
(public member function)
what returns the explanatory string
(public member function)

std::runtime_error::runtime_error

runtime_error( const std::string& what_arg ); (1)
runtime_error( const char* what_arg ); (2) (since C++11)
runtime_error( const runtime_error& other ); (until C++11)
runtime_error( const runtime_error& other ) (3) (since C++11)
noexcept;

1-2) Constructs the exception object with what_arg as explanatory string that can be
accessed through what().
3) Copy constructor.
If *this and other both have dynamic type std::runtime_error then
std::strcmp(what(), other.what()) == 0.
(since C++11)

Parameters

what_arg - explanatory string
other - another exception object to copy

Exceptions

1-2) May throw std::bad_alloc

Notes

Because copying std::runtime_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.

std::runtime_error::operator=

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

Assigns the contents with those of other.
If *this and other both have dynamic type std::runtime_error then
std::strcmp(what(), other.what()) == 0 after assignment.
(since C++11)

Parameters

other - another exception object to assign with

Return value

*this

std::runtime_error::what

virtual const char* what() const throw(); (until C++11)
virtual const char* what() const noexcept; (since C++11)

Returns the explanatory string.

Parameters

(none)

Return value

Pointer to a null-terminated string with explanatory information. The string is
suitable for conversion and display as a std::wstring. The pointer is guaranteed to
be valid at least until the exception object from which it is obtained is destroyed,
or until a non-const member function (e.g. copy assignment operator) on the
exception object is called.

Notes

Implementations are allowed but not required to override what().

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)