NAME¶

std::logic_error - std::logic_error

Synopsis¶

Defined in header <stdexcept>
class logic_error;

Defines a type of object to be thrown as exception. It reports errors that are a
consequence of faulty logic within the program such as violating logical
preconditions or class invariants and may be preventable.

No standard library components throw this exception directly, but the exception
types std::invalid_argument, std::domain_error, std::length_error,
std::out_of_range, std::future_error, and std::experimental::bad_optional_access are
derived from std::logic_error.

std-logic error-inheritance.svg

Inheritance diagram

Member functions¶

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

std::logic_error::logic_error

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

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::logic_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::logic_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::logic_error::operator=

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

Assigns the contents with those of other.
If *this and other both have dynamic type std::logic_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::logic_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)