Error code: Difference between revisions

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{{Short description|Code that indicates the nature of an error}}

{{distinguishDistinguish|Error correction code}}

In [[computing]], an '''error code''' (or a '''return code)''') is a numeric or [[Alphanumericals|alphanumeric]] code that indicates the nature of an error and, when possible, why it occurred.<ref>{{Cite web|url=https://www.computerhope.com/jargon/e/errorcode.htm|title=What is an Error Code?|website=www.computerhopeComputerHope.com|language=en |access-date=2020-01-22}}</ref> Error codes can be reported to end users of software, returned from [[Communication protocol|communication protocols]], or used within programs as a method of representing anomalous conditions.

== In consumer products ==

[[File:Error-code-e74.jpg|thumb|upright=1.3|alt=The error code E74. Above the large E 74 code is the message "System Error. Contact Xbox Customer Support." repeated in different languages.|thumb|Error E74 on the [[Xbox 360]], indicating a hardware failure.<ref>{{Cite web |title=Xbox Support |url=https://support.xbox.com/en-US/help/errors/xbox-360/error-code-e74 |access-date=2023-03-12 |website=support.xbox.com}}</ref>]]

Error codes are commonly encountered on displays of consumer electronics to users in order to communicate or specify an error. They can also be indicated by lights or beeps, e.g., if a device does not have a display. They are commonly reported by consumer electronics when users bring electronics to perform tasks that they cannot do (e.g., [[Division by zero|dividing by zero]]), or when the program within a device encounters an anomalous condition.

Error codes reported by consumer electronics are used to help diagnose and repair technical problems. An error code can be communicated to relevant support staff to identify potential fixes, or can simplify research into the cause of an error.

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== In computer programming ==

Error codes in computers can be passed to the system itself, to judge how to respond to the error. Often error codes come synonymous with an [[Exit status|exit code]] or a return value. The system may also choose to pass the error code to its user(s). The [[Blue screen of death]] is an example of how the [[Microsoft Windows|Windows operating system]] communicates error codes to the user.

Error codes can be used within a computer program to represent an anomalous condition. A computer program can take different actions depending on the value of an error code.

Different programming languages, operating systems, and programming environments often have their own conventions and standards for the meanings and values of error codes. Examples include:

* [[Unix-like]] systems have an [[errno.h]] header file that contains the meanings and values of error codes returned by [[system call]]s and library functions.<ref>{{man|2|intro|v7}}</ref><ref>{{man|3|errno|Linux}}</ref><ref>{{man|2|intro|Solaris}}</ref>

* [[Windows API|Microsoft Windows' application programming interfaces (APIs)]] have several different standards for error code values, depending on the specific API being used.<ref>{{Cite web |last=Passing |first=Johannes |title=Error Codes: Win32 vs. HRESULT vs. NTSTATUS |url=https://jpassing.com/2007/08/20/error-codes-win32-vs-hresult-vs-ntstatus/ |access-date=2023-03-12 |website=jpassing.com |language=en}}</ref><ref>{{Cite web |title=[MS-ERREF]: Overview |url=https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-erref/774ca55e-5e94-49ad-8710-c777fc717599 |access-date=2023-03-12 |website=learn.microsoft.com |languagedate=en-us30 March 2020 }}</ref>

The usage of error codes as an error handling strategy is often contrasted against using [[Exception handling|exceptions]] for error handling.<ref>{{Cite web |last=TylerMSFT |title=Modern C++ best practices for exceptions and error handling |url=https://learn.microsoft.com/en-us/cpp/cpp/errors-and-exception-handling-modern-cpp |access-date=2023-03-12 |website=learnLearn.microsoftMicrosoft.com |languagedate=en-us17 October 2022 }}</ref><ref>{{Cite web |title=Standard C++ |url=https://isocpp.org/wiki/faq/exceptions#exceptions-avoid-spreading-out-error-logic |access-date=2023-03-12 |website=isocppIsoCpp.org }}</ref>

* [[Linux]] defines its own [[errno.h]] header file, containing the meanings and values of error codes returned by [[System call|system calls]] and library functions.<ref>{{Cite web |title=errno(3) - Linux manual page |url=https://www.man7.org/linux/man-pages/man3/errno.3.html |access-date=2023-03-12 |website=www.man7.org}}</ref>

* [[Windows API|Microsoft Windows' application programming interfaces (APIs)]] have several different standards for error code values, depending on the specific API being used.<ref>{{Cite web |last=Passing |first=Johannes |title=Error Codes: Win32 vs. HRESULT vs. NTSTATUS |url=https://jpassing.com/2007/08/20/error-codes-win32-vs-hresult-vs-ntstatus/ |access-date=2023-03-12 |website=jpassing.com |language=en}}</ref><ref>{{Cite web |title=[MS-ERREF]: Overview |url=https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-erref/774ca55e-5e94-49ad-8710-c777fc717599 |access-date=2023-03-12 |website=learn.microsoft.com |language=en-us}}</ref>

The usage of error codes as an error handling strategy is often contrasted against using [[Exception handling|exceptions]] for error handling.<ref>{{Cite web |last=TylerMSFT |title=Modern C++ best practices for exceptions and error handling |url=https://learn.microsoft.com/en-us/cpp/cpp/errors-and-exception-handling-modern-cpp |access-date=2023-03-12 |website=learn.microsoft.com |language=en-us}}</ref><ref>{{Cite web |title=Standard C++ |url=https://isocpp.org/wiki/faq/exceptions#exceptions-avoid-spreading-out-error-logic |access-date=2023-03-12 |website=isocpp.org}}</ref>

==In communication protocols==

[[Communication protocol|Communication protocols]]s typically define a standard set of error codes, as a means of communicating the status or result of an operation between the entities in the system.

[[Communication protocol|Communication protocols]] typically define a standard set of error codes, as a means of communicating the status or result of an operation between the entities in the system.

Several high-level protocols in the [[TCP/IP stack]], such as [[HTTP]], [[File Transfer Protocol|FTP]], and [[Simple Mail Transfer Protocol|SMTP]], define their own standard sets of error codes:

* [[List of HTTP status codes]]

* [[List of FTP server return codes]]

* [[{{Section link|Simple Mail Transfer Protocol#Protocol overview]]}}

== In automobiles ==

Error codes in automobiles, sometimes referred to as trouble codes, indicate to a driver or car mechanic what is wrong with a vehicle before repairs are initiated.{{cnCitation needed|date=April 2023}}

In [[vehicle]]s with [[CAN bus|CAN buses]]es, error codes are often five-digit codes that pinpoint a particular car fault. Car owners can make use of an [[on-board diagnostics]] scanner or an owner's manual to identify the meaning of a trouble code. Five-digit diagnostic trouble codes typically consist of one letter and four numbers (e.g. P0123).{{cnCitation needed|date=April 2023}}

==See also==

* [[errno.h]], a header file in C that defines macros for reporting errors

* [[HRESULT]], a computer programming [[data type]] used for error codes

* [[Abort (computing)]]

* [[Aspect-oriented programming]]

* [[FailureBlue Screen of Death]]

* [[errno.h]], a header file in C that defines macros for reporting errors

* [[Exit status]]

* [[Failure]]

* [[HRESULT]], a computer programming [[data type]] used for error codes

* [[Static code analysis]]

* [[Blue Screen of Death]]

==References==

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==External links==

* [https://web.archive.org/web/20110115230351/http://www.barricane.com/c-error-codes-include-errno Lists of Linux errno values, both numeric and symbolic]

* [http://msdn.microsoft.com/en-us/library/ms681381(VS.85).aspx Microsoft system error codes]

* [http://support.microsoft.com/kb/310123 Microsoft Device Manager error codes]