# std::error_code

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< cpp‎ | error

Defined in header `<system_error>` |  |
class error_code; |  | (since C++11)

`std::error_code` is a platform-dependent error code. Each `std::error_code` object holds an error code originating from the operating system or some low-level interface and a pointer to an object of type std::error_category, which corresponds to the said interface. The error code values may be not unique across different error categories.

### Member functions

(constructor) | constructs an error code (public member function)
operator= | assigns another error code (public member function)
assign | assigns another error code (public member function)
##### Modifiers
clear | sets the error_code to value 0 in system_category (public member function)
##### Observers
value | obtains the value of the error_code (public member function)
category | obtains the error_category for this error_code (public member function)
default_error_condition | obtains the error_condition for this error_code (public member function)
message | obtains the explanatory string for this error_code (public member function)
operator bool | checks if the value is non-zero (public member function)

### Non-member functions

operator==operator!=operator<operator<=> (removed in C++20)(removed in C++20)(C++20) | compares two `error_code`s (function)
operator<< | outputs the value and the category name to an output stream (function)

### Helper classes

is_error_code_enum (C++11) | identifies a class as an error_code enumeration (class template)
std::hash<std::error_code> (C++11) | hash support for std::error_code (class template specialization)

### See also

error_condition (C++11) | holds a portable error code (class)
error_category (C++11) | base class for error categories (class)
make_error_code(std::errc) (C++11) | constructs an std::errc error code (function)

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