How To Get Hired -- What CS Students Need to Know

I've hired dozens of C/C++ programmers (mostly at the entry level). To do that, I had to interview hundreds of candidates. Many of them were woefully poorly prepared for the interview. This page is my attempt to help budding software engineers get and pass programming interviews.

Contents

What Interviewers are Tired Of

A surprisingly large fraction of applicants, even those with masters' degrees and PhDs in computer science, fail during interviews when asked to carry out basic programming tasks. For example, I've personally interviewed graduates who can't answer "Write a loop that counts from 1 to 10" or "What's the number after F in hexadecimal?" Less trivially, I've interviewed many candidates who can't use recursion to solve a real problem. These are basic skills; anyone who lacks them probably hasn't done much programming.

Speaking on behalf of software engineers who have to interview prospective new hires, I can safely say that we're tired of talking to candidates who can't program their way out of a paper bag. If you can successfully write a loop that goes from 1 to 10 in every language on your resume, can do simple arithmetic without a calculator, and can use recursion to solve a real problem, you're already ahead of the pack!

What Interviewers Look For

As Joel Spolsky wrote in his excellent essay The Guerrilla Guide to Interviewing:
1. Employers look for people who are Smart and Get Things Done
How can employers tell who gets things done? They go on your past record. Hence:
2. Employers look for people who Have Already Done Things
Or, as I was told once when I failed an interview:
3. You can't get a job doing something you haven't done before
(I was interviewing at HAL Computers for a hardware design job, and they asked me to implement a four-bit adder. I'd designed lots of things using discrete logic, but I'd always let the CPU do the math, so I didn't know offhand. Then they asked me how to simulate a digital circuit quickly. I'd been using Verilog, so I talked about event simulation. The interviewer reminded me about RTL simulation, and then gently said the line I quoted above. I'll never forget it.)

Finally, you may even find that

4. Employers Google your name to see what you've said and done

What This Means For You

What the above boil down to is: if you want to get a job programming, you have to do some real programming on your own first, and you have to get a public reputation, however minor, as a programmer. Don't wait for your school to teach you how to design and program; they might never get around to it. College courses in programming are fine, probably even necessary, but most programming courses don't provide the kind of experience that real programming gives, and real employers look for real programming experience.

Malcolm Gladwell wrote in Outliers,

... Ten thousand hours of practice is required to achieve the level of mastery associated with being a world-class expert -- in anything.
Seems about right to me. I don't know how many hours it takes to achieve the level of mastery required to program well enough to do a good job, but I bet it's something like 500. (I think I had been programming or doing digital logic in one way or another for about 500 hours before my Dad started giving me little programming jobs in high school. During my five years of college, I racked up something like several hundred hours programming for fun, several hundred more in CS/EE lab courses, and about two thousand on paid summer jobs.)

But How Can I Get Experience Without a Job?

If you're in college, and your school offers programming lab courses where you work on something seriously difficult for an entire term, take those courses. Good examples of this kind of course are Take several of this kind of course if you can; each big project you design and implement will be good experience.

Whether or not you're in college, nothing is stopping you from contributing to an existing Open Source project. One good way to start is to add unit or regression tests; nearly all projects need them, but few projects have a good set of them, so your efforts will be greatly appreciated.

I suggest starting by adding a conformance test to the Wine project. That's great because it gives you exposure to programming both in Linux and in Windows. Also, it's something that can be done without a huge investment of time; roughly 40 work hours should be enough for you to come up to speed, write a simple test, post it, address the feedback from the Wine developers, and repeat the last two steps until your code is accepted.

One nice benefit of getting code into an Open Source project is that when prospective employers Google you, they'll see your code, and they'll see that it is in use by thousands of people, which is always good for your reputation.

Quick Reality Check

If you want a quick reality check as to whether you can Get Things Done, I recommend the practice rooms at topcoder.com. If you can complete one of their tasks in C++ or Java within an hour, and your solution actually passes all the system tests, you can definitely program your way out of paper bag!

Good luck!

Please let me know whether this essay was helpful. You can email me at dank at kegel.com.

Shameless Plug

I'm looking for a few good interns. If you live in Los Angeles, and you are looking for a C/C++ internship, please have a look at my internship page.

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Last Change 18 Dec 2012
(C) Dan Kegel 2004,2005,2006,2011,2012

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