Error codes

In computer programming, error codes are enumerated messages that correspond to faults in a specific software application. They are typically used to identify faulty 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 codes, although both are commonly used together in error handling. Some of the most severe error codes visible to users are the "Blue Screen of Death" codes provided by the Microsoft Windows operating systems.

Error codes and exception handling

Error codes are slowly disappearing from the programmer's environment as modern object-oriented programming languages replace them with 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.