Lecture 27 Objectives (also listed under Lecture 24)

KNOW:

• To create data with references back and forth, we need to partially create the items, then hook them up with set-structure! (as in Lecture 23)
• Programs that can hit the same data item twice need to remember which ones they've visited to make sure the program stops.

BE ABLE TO:

• Recognize when a variable is needed to record which data items have been visited.

Sample Exam Question:

In the webpage example from today's lecture, we used a variable to record the fact that a particular webpage had already been visited. In a previous offering of this course, a student suggested that the "visited" variable be defined locally within the function count-pages. That won't work - why not?