Prepping for a job interview is a little like a politician prepping for a debate. There are certain questions you can count on hearing, and you prepare canned responses to them. In the job interview these would be things like, "Why did you leave your last job?" and "Where do you see yourself in five years?"
Then there are the technical screening questions. They'll focus on your experience and knowledge. Typically you'll get some basic stuff to begin with, just to see if you really did all those things you put on your resume.
Then you start getting to the interesting questions. The ones that don't have a clear "right" answer. Or do they? Does the interviewer have something specific in mind? Will I blow it by not coming up with the right answer?
Take these two technical questions as an example:
1) When or why would you consider using an RDBMS (like MySQL etc) as opposed to a desktop database (sqlite etc)?Programmers tend to enter the field, and stay in it, because they're good at finding right answers. Computers are (mostly) deterministic. The upside for the programmer is that they know with certainty when they've solved a problem. The downside is that they know with frustrating certainty when they haven't. They can't just dress up "because I said so" in reasonable-sounding logic and turn it in. Their program has to actually work.
2) When creating a function how many parameters would you allow that function to handle?
But the questions above don't have right answers. They aren't intended to see if someone knows how to implement a given solution. They're intended to see if someone knows how to ask the right questions to choose the right solution.
Anyone can look up a linked list implementation, or a quicksort. Most interviewers are more interested in identifying the guy who can figure out which one to use.
For the parameters question above, I'd want somebody to state a basic rule of thumb -- probably something from 3-10 "feels" like a reasonable starting point. But they should also explain their reasoning, which might be along the lines that too many parameters is likely to indicate too much going on in one function. Then possibly present an exceptional case where a high parameter count would be preferred.
Maybe there would be some discussion around passing an array of name/value pairs instead of multiple individual parameters, or named parameters, default values, etc. Or pro/con on passing all the values for an object in the new() declaration, vs. a basic instantiation and then multiple set() calls.
These specifics are not the "one right answer". They're examples of the kind of answer I'd hope to hear. If I asked you the question and you couldn't either float some ideas or ask some reasonable questions, I'd take it as a sign of lack of experience. Interviews are not a multiple-choice test, they're essay format. If the interviewer or the candidate acts like it's multiple-choice, they're wrong.
Trying hard to not get itIf you're interviewing people for entry-level jobs, maybe you do just need to know that the candidate can implement a particular pattern. Once you get past entry level, you'll want to see that the candidate can identify which pattern they should implement. Best is to find a candidate who knows why to choose a particular pattern. Which means they know other patterns and why not to choose one of them instead.
You can make it through a class in school only learning the one technique that you're going to be tested on. That's why entry level people aren't trusted to make choices, just do what they're told. Once you get out of the classroom, you have the freedom to re-invent everything, making the same mistakes everyone has made before you. The more ways you've seen to solve a given problem, the more choices you have. I'm not interested in finding someone who's always going to choose the same solution as me. I want someone who knows the general principles and how to prioritize competing goals.
But some programmers will get nervous, and others downright hostile, if you ask a question without a clear right answer. As far as they're concerned, it's a "bad question" that you shouldn't even ask. Apparently any question where the answer starts with "It depends" is a trick question, and even asking it is an insult.
How you should answerRemember those courses you took where the instructor would tell you to show your work? Even if the answer was wrong, you could get partial credit for having the right approach. When interviewing it's all about showing the work. The "right" answer is almost incidental.
But sometimes there is a right answer. Doesn't that matter? Absolutely. And knowing whether you're dealing with one of those questions or not is an important skill.
If my goal is to evaluate whether someone knows how to clarify an incomplete requirement, I don't start by telling him, "Now I'm going to give you an incomplete requirement to see if you know to clarify it." I ask a question as though there is a right answer and see what they say.
So maybe you read all of this and think that now you know what I'm looking for. That doesn't help you with someone else who may have a different plan. The good news is that it doesn't matter, as long as you answer truthfully.
If the interviewer is looking for a specific answer and you give multiple alternatives, you may be giving a better answer than what he expected. Or maybe he'll disagree with your reasoning and decide that you are wrong. Do you want to work for someone who will shoot down your ideas?
Or the question was supposed to be open-ended but you give a single definitive answer. A good interviewer will prompt you to explain, maybe even asking about specific alternatives. Did you have a good reason to discount those answers? Explain it. Did you not think about that? Admit it. Maybe you're really not a good fit for this position.
Sure, you need a paycheck. But unless you are desperate you also need a good fit. If you and the person you'll be working for don't see things the same way, you won't get that fit. So instead of trying to overanalyze what the interviewer "really meant", just answer as honestly and completely as you think you can. If you, the interviewer and the position are a match, all that's left is to talk about the money.