std::hash<std::error_code>

Defined in header `<system_error>`
template<> struct hash<error_code>;		(since C++11)

The template specialization of std::hash for std::error_code allows users to obtain hashes of objects of type std::error_code.

Language
Standard library headers
Concepts
Utilities library
Strings library
Containers library
Algorithms library
Iterators library
Numerics library
Input/output library
Localizations library
Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)
Technical Specifications

Type support (basic types, RTTI, type traits)
Dynamic memory management
Error handling
Program utilities
Variadic functions
Date and time
Function objects
initializer_list (C++11)
bitset
hash (C++11)
Relational operators
rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=
Pairs and tuples
pair
tuple (C++11)
piecewise_construct_t (C++11)
piecewise_construct (C++11)
integer_sequence (C++14)
Swap, forward and move
swap
exchange (C++14)
forward (C++11)
move (C++11)
move_if_noexcept (C++11)
Type operations
declval (C++11)
as_const (C++17)

Exception handling
exception
uncaught_exceptionuncaught_exceptions (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
unexpected (deprecated)
bad_exception
unexpected_handler (deprecated)
get_unexpected (C++11)(deprecated)
set_unexpected (deprecated)
Exception categories
logic_error
invalid_argument
domain_error
length_error
out_of_range
runtime_error
range_error
overflow_error
underflow_error
Error codes
Error codes
errno
Assertions
assert
system_error facility
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)

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<<
Helper classes
is_error_code_enum
hash<std::error_code>