Interview questions

[presidentender]

In SoundTheSurrender's thread, he mentions that they asked questions in his phone interview to which he didn't know the answers. Now, we could make a "skills you need" thread, which would quickly devolve into bickering about which skills are actually important (Do soft skills count? Do we need to understand graphical programming and assembly? Is C# a better bet than Java?) but I think it would be better make a list of questions that we've all been asked (or asked, if you've run interviews) to promote productive study.

The potential problem with this type of thing in other cases is that it might encourage us beginners to study the questions and answers, instead of the concepts behind them. However, in CS, software engineering, and programming, I don't think it's really possible to answer these questions without understanding what's actually going on. Furthermore, by giving just the questions instead of the answers, we'd make that type of thing impossible.

My questions:
How would you select a set of everyone with the last name of "Smith" from a database with fields for first name, last name, and phone number?

How would you check every checkbox on a web page?

What is n-tier architecture? (3-tier architecture, depending on who asks.) Describe it.

What does a compiler do? (They kept pressing this one further into theory until I said "I don't know.")

What happens when you press the "L" key on the keyboard (when you have a text editor open) between the time you press the key and the time the computer displays the character?

What are the principles of object-oriented programming?

Why do we use quicksort instead of bubblesort?

What is a hash table?

I imagine in higher-caliber interviews, there are language-specific questions: describe LINQ in C#, for instance, or generics in Java.

 

[ivan2]

Notable questions on top of my head, note that I have only interviewed for software engineering jobs so there isn't any machine leveled stuff =

-Java thread safe questions (ranging from ArrayList vs Vector, Class locking vs Object locking, to full blown on site coding exercise)

-Table design and SQL query (to my surprise nobody had ever asked me to design transactions, maybe deadlocks were always an after thought?)

-Know something about hash table or general indexed/treeed data structures, asked you to design a program that commonly involves usage of these data structures without explicitly telling you that you should use them for efficiency.

-Smartass one way linked list questions, to be specific:

How do you know if there is a cycle within the linked list. The cycle can happen anywhere, for example the linked list can either look like a 0 or a 6.

How can you get the nth to the last element of a linked list efficiently?

- Polymorphism, this is an interview buzzword especially for fresh out of colleges.

 

[drebo]

I've been asked to describe the differences between one-to-one, one-to-many, and many-to-many relationships, and to describe an example for each. Sounds elementary, but you'd be surprised how many people you can weed out right away by this question.

I've seen generic questions regarding process time scheduling, requirements, and limitations.

One interview asked me which layer of the OSI model was considered the network layer. This was for a programming job.

Conflict resolution questions are always popular.

 

[tfinch2]

What are the two main XML parsing styles, how do they differ, and in what situation would you choose one over the other?

 

[Gunslinger08]

You'd be amazed by how many candidates can't even answer simple practical questions like how to loop through an array, sort a collection, write a recursive method, etc.

 

[Evadman]

I was asked this question (probably screwed up the wording). There are 100 lockers, and 100 people to open or close the lockers. The lockers start closed and the first person opens every locker. The 2nd person closes every 2nd locker (2, 4, 6 8, 10, etc) the 3rd person changes every 3rd locker (close #3, open #6, close #9, etc) the 4th person does every 4th locker. What is the final status of every locker after the 100th person?

the answer is every locker number that has an odd number of factors. In other words, every perfect square. I solved it during the interview though brute force and an access database using 100 queries fired by a vbscript. I think that impressed the guy more than the actual answer

 

[recoil80]

My first full time job was for a big agency that was about to start an embedded business unit.
These were the questions for the technical interview:

- Tell me what you know about a kernel
- Differences between RISC and CISC
- What is a cache?
- Tell me about the TCP/IP
- Differences between process and thread
- What is a file system?
- What is the virtual memory?
- What is DMA?
- What do you know about assembly?
I think I was asked some other questions about software engeneering, like the waterfall model but I don't remember exactly what was the question about...

Then I was asked to write some C code about ordering a list (it's too simple, but most of the candidates struggle...), doing some operations like setting bits in memory, dealing with AND/OR/XOR and stuff like that.

I really enjoyed the interview, and I was hired
If I'll be in charge of doing the interviews in the future I think I'll ask questions like those, for an embedded BU of course. I think you need to be very technical, because too many people get their degree without being able to write some pieces of code...

 

[EricMartello]

For me, answering these kind of questions off the top of my head would prove challenging - not because I don't know, but because I can't put it in words. It's similar to asking me for directions...I don't know the names of the streets or the intersections, I just remember how to get there, so if someone asked me where such and such place is, it would seem that I don't know even though I do.

I understand why some companies might think that having someone who can answer these questions is better than someone who can't, but if you are trying to evaluate someone's programming ability it is better just to give them an assignment or instruct them to create functions/algorithms in whatever language is applicable to the position rather than asking them to transpose programming concepts into English.

 

[degibson]

The most important thing is finding the right person -- not finding the person with the right knowledge to answer the questions. Its the way the questions are answered that is most important (background knowledge helps, of course).

 

[recoil80]

Originally posted by: degibson
The most important thing is finding the right person -- not finding the person with the right knowledge to answer the questions. Its the way the questions are answered that is most important (background knowledge helps, of course).

I agree with you. A job interview is not an exam, you are no more a student.
I think it's a good idea to let the person solve a problem in some language (let's say C, Java, C#), just to make sure he's able to think about it, and to come up with a solution. It doesn't matter if you forget to put a ; or if you don't remember how to read a variable from the stdin.

Anyway I don't find it unfair to ask for specific questions, if you are trying to fill a particular position. The interview I talked about was for an embedded business unit. You are not supposed to hire a guy who is smart in Java, loves dealing with databases but knows nothing about operating system and networks.

 

[otherwise]

Some really basic C++ questions that people stumble on for some reason (off the top of my head):

1. When do you use a pointer? auto pointer? smart pointer? What's the difference between the three?
2. Explain the difference between stack and heap lifetimes.
3. Your program is leaking memory. How do you find it?
4. Is it acceptable to not explicitly delete "new'd" memory in a singleton? If not -- how do you do it?
5. What's the difference between the different casts.
6. How would you code a simple timer, or what framework would you use to handle it for you?
7. Can you do anything with templates that you can't with [C#/Java] generics?


Really though any serious job interview is going to focus on problems, the language questions are just a filter.