Namespaces
Variants
Views
Actions

std::format_error

From cppreference.com
< cpp‎ | utility‎ | format
 
 
Utilities library
General utilities
Date and time
Function objects
Formatting library (C++20)
(C++11)
Relational operators (deprecated in C++20)
Integer comparison functions
(C++20)
Swap and type operations
(C++14)
(C++11)
(C++11)
(C++11)
(C++17)
Common vocabulary types
(C++11)
(C++17)
(C++17)
(C++17)
(C++17)

Elementary string conversions
(C++17)
(C++17)
 
Formatting library
Formatting functions
(C++20)
(C++20)
(C++20)
(C++20)
Formatter
(C++20)
Formatting arguments
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.

cpp/error/exceptioncpp/error/runtime errorstd-format error-inheritance.svg
About this image

Inheritance diagram

Contents

[edit] 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

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

[edit] Example

[edit] See also