Problem Set 2

What to Do

  1. Log into
  2. Run update50 in your codespace’s terminal window to ensure your codespace is up-to-date and, when prompted, click Rebuild now
  3. Submit Readability
  4. Submit one of:
  5. Submit this form

If you submit both Caesar and Substitution, we’ll record the higher of your two scores.

Note that each problem invites you to try out the staff’s own solution thereto using a tool called CS50 Sandbox, which is similar to VS Code but configured to have only a terminal window in which you can execute the staff’s solution (but not see its code).

When to Do It

By .

How to Get Help

  • Browse or search for answers on Ed!
  • Verbalize your logic to a rubber duck (whether actual or virtual!) and see if you hear any illogic in your own words!
  • Attend office hours!


  • Try out any of David’s programs from class via Week 2’s examples.
  • To see the manual pages for C functions, visit
  • If you see any errors when compiling your code with make, focus first on fixing the very first error you see, scrolling up as needed. If unsure what it means, try asking help50 for help. For instance, if trying to compile readability, and
    make readability

    is yielding errors, try running

    help50 make readability