Lab 3.04 what is it supposed to do?

[jdonwells]

Lab 3.04 has sections Problem 1, Problem 2, Problem 3. Students are asked to decide if there is a problem in the code. But we never tell them what the code is supposed to do.

The example itself seems a bit contrived. I can't imagine anyone writing something like that. This is a bad example to have students study. Let's not do that.

For anyone trying to figure out what we are trying to show them:

1. We are creating local variables in the function named the same as the global variables, but they are assigned after reference.
2. We are creating local variables named the same as global variables, but they seem to be assigned the wrong values.
3. We are using the global variables in the function such that your favorite pet is always cat.

[dvgrn]

I remember this exercise, from when I was teaching it last year! This was absolutely one of the most difficult examples to teach from. I checked in some minor changes so that the code actually worked without errors, but I didn't have a clear plan for actually adjusting it so that it made sense.

If I remember right, we ended up picking a small subset of the code, walking through it, and asking some very specific questions about it, and then moving on before anyone could get too confused -- and covering global vs. local variables in other contexts later, where they made more sense.

I agree 100% that the sample code as it stands does not do anything useful with global and local variables. It's kind of a programmer's shell game, designed apparently to trick everyone into getting the wrong answer. Any redesign would almost certainly be an improvement!