std::error_code::error_code

 

C++

Compiler support

Freestanding and hosted

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Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Diagnostics library

Memory management library

Metaprogramming library (C++11)

General utilities library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

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Text processing library

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Date and time library

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Filesystem library (C++17)

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Technical specifications

Symbols index

External libraries

 

Utilities library

Language support Type support (basic types, RTTI) Library feature-test macros (C++20) Program utilities Variadic functions initializer_list (C++11) is_constant_evaluated (C++20) is_within_lifetime (C++26) source_location (C++20) Coroutine support (C++20) Contract support (C++26) Three-way comparison three_way_comparablethree_way_comparable_with (C++20)(C++20) strong_ordering (C++20) weak_ordering (C++20) partial_ordering (C++20) common_comparison_category (C++20) compare_three_way_result (C++20) compare_three_way (C++20) strong_order (C++20) weak_order (C++20) partial_order (C++20) compare_strong_order_fallback (C++20) compare_weak_order_fallback (C++20) compare_partial_order_fallback (C++20)   is_eqis_ltis_lteq (C++20)(C++20)(C++20)   is_neqis_gtis_gteq (C++20)(C++20)(C++20)

General utilities Function objects Bit manipulation (C++20) C-style bit manipulation (C++26) bitset hash (C++11) Relational operators (deprecated in C++20) rel_ops::operator!=rel_ops::operator>    rel_ops::operator<=rel_ops::operator>= Integer comparison functions cmp_equalcmp_lesscmp_less_than (C++20)(C++20)(C++20)   cmp_not_equalcmp_greatercmp_greater_than (C++20)(C++20)(C++20) in_range (C++20) Swap and type operations swap ranges::swap (C++20) exchange (C++14) declval (C++11) to_underlying (C++23) forward (C++11) forward_like (C++23) move (C++11) move_if_noexcept (C++11) as_const (C++17) Common vocabulary types pair tuple (C++11) optional (C++17) any (C++17) variant (C++17) tuple_size (C++11) tuple_element (C++11) apply (C++17) make_from_tuple (C++17) expected (C++23)

 

Diagnostics library

Exception handling exception uncaught_exceptionuncaught_exceptions (until C++20*)  (C++17) exception_ptr (C++11) make_exception_ptr (C++11) current_exception (C++11) rethrow_exception (C++11) nested_exception (C++11) throw_with_nested (C++11) rethrow_if_nested (C++11) Exception handling failures terminate terminate_handler get_terminate (C++11) set_terminate bad_exception unexpected (until C++17*) unexpected_handler (until C++17*) get_unexpected (until C++17*) set_unexpected (until C++17*) Error numbers Error codes errno Assertions assert

Exception categories logic_error invalid_argument domain_error length_error out_of_range runtime_error range_error overflow_error underflow_error tx_exception (TM TS) System error error_category (C++11) generic_category (C++11) system_category (C++11) error_condition (C++11) errc (C++11) error_code (C++11) system_error (C++11) Stacktrace stacktrace_entry (C++23) basic_stacktrace (C++23) Debugging support is_debugger_present (C++26) breakpoint_if_debugging (C++26) breakpoint (C++26)

 

std::error_code

Member functions

error_code::error_code

error_code::operator=

error_code::assign

Modifiers

error_code::clear

Observers

error_code::value

error_code::category

error_code::default_error_condition

error_code::message

error_code::operator bool

Non-member functions

operator==operator!=operator<operator<=> (until C++20)(until C++20)(C++20)

operator<<

Helper classes

is_error_code_enum

hash<std::error_code>

 

error_code() noexcept;	(1)	(since C++11)
error_code( int ec, const error_category& ecat ) noexcept;	(2)	(since C++11)
template< class ErrorCodeEnum > error_code( ErrorCodeEnum e ) noexcept;	(3)	(since C++11)
error_code( const error_code& other ) = default;	(4)	(since C++11) (implicitly declared)
error_code( error_code&& other ) = default;	(5)	(since C++11) (implicitly declared)

Constructs new error code.

1) Constructs error code with default value. Equivalent to error_code(0, std::system_category().

2) Constructs error code with ec as the platform-dependent error code and ecat as the corresponding error category.

3) Constructs error code from an error code enum e. Equivalent to make_error_code(e), where make_error_code is only found by argument-dependent lookup. This overload participates in overload resolution only if std::is_error_code_enum<ErrorCodeEnum>::value is true.

4,5) Implicitly defined copy constructor and move constructor. Initializes the error code with the contents of the other.

Parameters

other	-	another error code to initialize with
ec	-	platform dependent error code to construct with
ecat	-	error category corresponding to ec
e	-	error code enum to construct with

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 3629	C++11	only std::make_error_code overloads were used	ADL-found overloads are used

See also

make_error_code(std::errc) (C++11)	creates error code value for errc enum e (function)
make_error_code(std::io_errc) (C++11)	constructs an iostream error code (function)
make_error_code(std::future_errc) (C++11)	constructs a future error code (function)

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