computer programming Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as anal ...

, a return code or an error code is a numeric or

alphanumeric Alphanumericals or alphanumeric characters are a combination of alphabetical and numerical characters. More specifically, they are the collection of Latin letters and Arabic digits. An alphanumeric code is an identifier made of alphanumeric c ...

code that is used to determine the nature of an error and why it occurred. They are also commonly found in consumer electronics and devices when they attempt to do something they cannot do (e.g., dividing by zero) or fail to do and they can be passed off to error handlers that determine what action to take. In

vehicles A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), ...

, error codes are five-digit codes that pinpoint a particular car fault. Car owners can make use of an

on-board diagnostics On-board diagnostics (OBD) is a term referring to a vehicle's self-diagnostic and reporting capability. OBD systems give the vehicle owner or repair technician access to the status of the various vehicle sub-systems. The amount of diagnostic inf ...

scanner to identify a trouble code. The five-digit Diagnostic trouble code typically consists of one letter and four numbers (e.g
P0123

In consumer products

Error codes can also be used to specify an error, to simplify research into the cause and how to fix it. This is commonly used in consumer products when something goes wrong, such as the cause of the Blue Screen of Death, to make it easier to pinpoint the exact problem the product is having. There is no definitive form of an error code. Some styles use decimal or

hexadecimal In mathematics and computing, the hexadecimal (also base-16 or simply hex) numeral system is a positional numeral system that represents numbers using a radix (base) of 16. Unlike the decimal system representing numbers using 10 symbols, he ...

numbers, others use alphanumeric codes and some use a phrase describing the error.

In computing

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 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 a popular

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

communicates error codes to the user.

In networking software

Network protocol A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any kind of variation of a physical quantity. The protocol defines the rules, syntax, semantics and synchroniza ...

s typically support returning status codes. In the

TCP/IP stack The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...

, it's a common feature of higher level protocols. For example: *

List of HTTP status codes This is a list of Hypertext Transfer Protocol (HTTP) response status codes. Status codes are issued by a server in response to a client's request made to the server. It includes codes from IETF Request for Comments (RFCs), other specifications, ...

List of FTP server return codes FTP server return codes always have three digits, and each digit has a special meaning.RFC 959 The first digit denotes whether the response is good, bad or incomplete: The second digit is a grouping digit and encodes the following information: ...

* Simple Mail Transfer Protocol#Protocol overview

In Automobiles

Error codes in automobiles indicate to a driver or car mechanic what is wrong with a vehicle before repair(s) are initiated. A car is liable to display as many fault codes as possible on the OBD-II scanner, it all depends on the state of the engine system.

Error codes and exception handling

Error codes are passed to

exception handling In computing and computer programming, exception handling is the process of responding to the occurrence of ''exceptions'' – anomalous or exceptional conditions requiring special processing – during the execution of a program. In general, an ...

in programming languages that support it. These are passed to log files and the parent process to determine what action to take.

References

{{Reflist

External links

Lists of Linux errno values, both numeric and symbolicMicrosoft system error codesMicrosoft Device Manager error codes
Software