std::format_error

 

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Formatting library

Formatting functions

format (C++20)

format_to (C++20)

format_to_n (C++20)

formatted_size (C++20)

vformat (C++20)

vformat_to (C++20)

Formatter

formatter (C++20)

basic_format_parse_contextformat_parse_contextwformat_parse_context (C++20)(C++20)(C++20)

basic_format_contextformat_contextwformat_context (C++20)(C++20)(C++20)

Formatting arguments

basic_format_arg (C++20)

basic_format_argsformat_argswformat_args (C++20)(C++20)(C++20)

visit_format_arg (C++20)

make_format_argsmake_wformat_args (C++20)(C++20)

Format error

format_error (C++20)

 

Defined in header <format>
class format_error;		(since C++20)

Defines the type of exception object thrown to report errors in the formatting library.

Inheritance diagram

Member functions

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

std::format_error::format_error

format_error( const std::string& what_arg );	(1)	(since C++20)
format_error( const char* what_arg );	(2)	(since C++20)
format_error( const format_error& other ) noexcept;	(3)	(since C++20)

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::format_error then std::strcmp(what(), other.what()) == 0.

Parameters

what_arg	-	explanatory string
other	-	another exception object to copy

Exceptions

1-2) May throw std::bad_alloc

Notes

Because copying std::format_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::format_error::operator=

format_error& operator=( const format_error& other ) noexcept;		(since C++20)

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

Parameters

other

-

another exception object to assign with

Return value

*this

std::format_error::what

virtual const char* what() const noexcept;		(since C++20)

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::runtime_error

Inherited from std::exception

Member functions

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