It depends which ones you don't know
I've actually done a few interviews for candidates at work (video game company). The sort of questions you get asked for a programming job interview fall into 4 camps:
1. General "are you a serial killer" questions that screen out... unpleasant people. Things like: do you have any outside hobbies? Why do you want to work for us? Have you ever punched a client in the face? Is so, why? If not, why not?
2. Technical questions about coding. Things like: write a binary sort. Implement
strtok to spec. Reverse a linked list. Add two twos-complement numbers using just binary operations (bitwise AND, OR, XOR, COMPLEMENT). When would you use obscure feature X from the
C++ FAQ.
3. Technical math questions. Things like: what is a matrix? What do you use it for? Can you do basic linear algebra? Solve for X. Can you do Algebgra II? Solve for x. Can you do trig? How far can you see on a clear day? (using the fact that the earth is 6000 km radius and a person is 2 meters tall).
4. Braintwisters: There are three lightbulbs in the other room that you can't see, and three lightswitches in the same room. How can you tell which lightswitches correspond to which lightbulbs?
Replace math questions with database questions if you're aiming at more that sort of programming. Replace C++ with Python/Ruby/Lua/Java depending on the industry you're aiming for.
The idea is usually that the questions are either things you should know off hand, or are too hard for you to just
know, and instead the interviewers get to see your thought process as you fumble trying to solve it.
