When is it appropriate to use error codes?

Question

In languages that support exception objects (Java, C#), when is it appropriate to use error codes? Is the use of error codes ever appropriate in typical enterprise applicati

Answer 1

Error codes are for if you want to send them to the user. If not, use an exception.

Answer 2

WITHIN a program one should always use exceptions instead of error codes. However, exceptions can't propagate beyond a program. Any time the error must leave the program you are left with error messages or error codes.

For simple things that will always be human-operated error messages without codes are fine. You can say "File not found" without giving it an error code. However, if it might be another computer on the other end then you should give error codes in addition. You don't want to break the other system when you change it to "File <x> not found".

Answer 3

I'm a newbie to stack overflow but...

I believe that error codes tend to be used or useful for dealing with erroneous situations that require an end-user of sorts to get involved to rectify a situation. If your code is to be maintained by another developer then exceptions is the way to go. However, in a situation where there is a problem:

• in the environment that your application is running

• with communication between your app and some other entity (web server, database, socket, etc)

• that a device or device driver indicates (hardware failure maybe?)

then error codes may make sense. For example, if your app attempted to log into a database on behalf of your end-user, but the DB was unreachable for authentication (DB is off-line, cable is unplugged) then an error code/description combo might help the end-user rectify the problem.

Again at the developer/engineer level who will be able to touch the source code (traditional debugging and testing techniques) and modify it, use exceptions.

Hope this helps...

--jqpdev

Answer 4

Error codes are old-school. They are of little to no value at all.

The only possible value to an error code is that it can identify a very specific circumstance. You could have a code for each point in the code base that can throw an exception. This would allow you to narrow down very precisely what the problem must be.

But nobody cares about that level of detail. Who wants to maintain such a mess. It would leave you with codes that meant something like "condition A and B but not C due to state S". It's more effort than it's worth to try to work out exactly what that means. A stack trace will be more valuable in telling you where in the program the problem occurred.

I learned to program computers before exceptions were a widespread technique. I'm so glad we got exceptions instead!