Course placement

Written by Keith Schwarz

The CS department offers many programming courses and it can be difficult to know exactly where to begin. This handout provides a general overview of these classes and some advice about selecting the class that's right for you.

If you have any questions, please feel free to come talk to the course staff! We'd be happy to offer one-on-one advice.

CS106A: Start here!

CS106A is our first-quarter programming course. It teaches the widely-used Python programming language along with good software engineering principles. If you're interested in learning how to program a computer, this is the place to start. CS106A has no prerequisites – it's open to everyone! The course is explicitly designed to appeal to humanists and social scientists as well as hard-core techies. In fact, most CS 106A graduates end up majoring outside of the School of Engineering. The course requires no previous background in programming, but does require considerable dedication and hard work.

We've found that some high school CS classes are more rigorous than others. If you do have high school CS experience, we recommend reviewing the syllabus for CS106A to get a sense of what it covers. If you feel that you've seen all these topics before, you may want to start off in CS106B.

We recommend that you take CS106A if

  • You are interested in learning to program computers.
  • You have little to no prior programming experience.

We recommend that you not take CS106A if

  • You have prior programming experience at a level comparable to an introductory college course (for example, if you scored a 4 or 5 on the AP CS exam).
  • You have prior programming experience and want to learn how to program in Python.

CS106B: Next step

CS106B is our second course in computer programming. It focuses on techniques for solving more complex problems than those covered in CS106A and for analyzing program efficiency. Specifically, it explores fundamental data types and data structures, recursive problem solving, graph algorithms, and basic algorithmic analysis.

CS106B assumes you have programming experience at the level of CS106A, though you don't necessarily have to have taken our CS106A course in order to take CS106B. If you're experienced with basic control structures (conditions, loops), variables, arrays/lists, maps, and program decomposition, then you should be ready to take CS106B.

CS106B is taught using the C++ programming language, but uses C++ more as a vehicle for ideas than as an object of study. If you're interested in studying C++ in depth, consider looking into CS106L.

We recommend that you take CS106B if

  • You have prior programming experience at the level of CS106A.
  • You are interested in learning more about problem-solving with computers.
  • You've programmed before but have not seen recursion, data structures, or algorithmic analysis.

We recommend that you not take CS106B if

  • You already have completed equivalent coursework elsewhere.
  • You have little to no prior programming experience.
  • You have prior programming experience and want to specifically learn C++ programming.

Visit the CS106B website.

Can I skip the intro courses altogether?

Many students entering Stanford today have had considerable programming experience in high school or from their own independent work with computers. If you are in that position, the idea of starting with a beginning programming course—even an intensive one like CS 106B—seems like a waste of time. Your perception may in fact be correct. In our experience, there are somewhere between 10 and 15 students in each entering class who should start at a more advanced point in the sequence. Below we talk about some of these more advanced classes (CS107 and CS107E).

For most of you, however, the right place to start is with the CS 106 series. Most high-school computing courses are somewhat weak and provide little background in modern software engineering techniques. By taking CS 106, you will learn how the CS department at Stanford approaches programming and get a solid foundation for more advanced work. If you’re unsure where you should start the programming sequence, please talk with us.

CS107: How it all works

After completing the intro programming sequence, CS107 takes you under the hood to learn the ins and outs of computer systems. It explores how high-level programming constructs are represented internally inside the computer and how those internal representations affect program behavior and performance. Along the way, it provides programming maturity and exposure to developing software in a Unix environment.

CS107 has CS106B as a prerequisite and assumes an understanding of fundamental programming techniques and good programming style. As a result, it's rare for incoming students to jump directly into CS107 and to skip the CS106 series entirely. Typically, we'd only recommend this to students with a background comparable to CS106A/B and who already have good programming style. Most students, even those who go on to be CS majors, usually begin in the CS106 sequence.

We recommend that you take CS107 if

  • You have completed CS106B or have the equivalent programming background, including familiarity with recursion and fundamental data structures (binary trees, dynamic arrays, linked lists, graphs, etc.)
  • You have experience writing readable code – writing comments, decomposing problems into smaller pieces, etc.

We recommend that you not take CS107 if

  • You have never before taken a class in computer programming.
  • You have prior programming experience but have not met the postconditions of CS106B.

Visit the CS107 website.

CS107E: How it works, embedded

CS107E is version of CS107 that covers similar topics but which focuses on programming a small computer that can easily fit into the palm of your hand. The class is smaller and more project-oriented than CS107 and lets you play around with small embedded devices to see how low-level systems concepts directly let you control physical devices. The CS107E FAQ offers perspective on advice on choosing between 107 and 107E.

We recommend that you take CS107E if

  • You meet all the requirements for CS107.
  • You enjoy working on open-ended projects.

We recommend that you not take CS107E if

  • You're nervous about taking CS107 and want to satisfy that requirement in a different way.

Visit the CS107E website.