Error code: Difference between revisions

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

{{unreferenced|date=August 2012}}

{{Distinguish|Error correction code}}

In [[Programming language|computer programming]], '''error codes''' are enumerated messages that correspond to faults in a specific [[software application]]. They are typically used to identify faulty [[computer hardware|hardware]], [[software]], or incorrect user input in programming languages that lack [[exception handling]], although they are sometimes also used in conjunction with exception handling. "Error codes" are not to be confused with ''[[return code]]s'', although both are commonly used together in error handling.

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=ComputerHope.com |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.

==Error codes and exception handling==

Error codes are slowly disappearing from the programmer's environment as modern [[Object-oriented programming|object-oriented]] [[programming languages]] replace them with [[Exception handling|exceptions]]. Exceptions have the advantage of being handled with explicit blocks of code, separate from the rest of the code. While it is considered poor practice in methodologies that use error codes and return codes to indicate failure, programmers often neglect to check return values for error conditions. That negligence can cause undesirable effects, as ignored error conditions often cause more severe problems later in the program. Exceptions are implemented in such a way as to separate the error handling code from the rest of the code. Separating the error handling code from the normal logic makes programs easier to write and understand, since one block of error handling code can service errors from any number of function calls. Exception handling also makes the code more readable than implementations with error codes, since exception handling does not disrupt the flow of the code with frequent checks for error 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.|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.

There is no definitive format for error codes, meaning that error codes typically differ from/between products and or companies.

== 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 |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 |date=30 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=Learn.Microsoft.com |date=17 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=IsoCpp.org }}</ref>

==In communication protocols==

[[Communication protocol]]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.

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.{{Citation needed|date=April 2023}}

In [[vehicle]]s with [[CAN bus]]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).{{Citation needed|date=April 2023}}

==See also==

* [[Abort (computing)]]

* [[Aspect-oriented programming]]

* [[Blue Screen of Death]]

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

* [[AbortExit (computing)status]]

* [[Failure]]

*[[Aspect-oriented programming]]

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

*[[Exit status]]

* [[Static code analysis]]

*[[Failure]]

*[[Static code analysis]]

==References==

{{Reflist}}

==External links==

* [http://supportmsdn.microsoft.com/kben-us/310123library/ms681381(VS.85).aspx Microsoft Device Managersystem error codes]

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

* [http://msdnsupport.microsoft.com/en-uskb/library/ms681381(VS.85).aspx310123 Microsoft systemDevice Manager error codes]

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

[[Category:Computer networkingSoftware]]

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[[Category:Computer networking]]