CSC151 2007S, Class 17: Conditionals

Admin:
* My children's school has a 10 a.m. start today, so I will not be in class.  
  Try to do your work with Max's help.
* Questions on the homework will have to come via email.  Sorry.
* I've added a number of pages to the course reference site, 
  available through the Reference:Primary link at the top of every page.
* Read for Wednesday: List Iteration.
* Extra credit for this Thursday's Thursday Extra:
  Ian Athanasakis talks about his internship at Google.
* Max's office hours: Tonight 8-9pm

Overview:
* Choosing between two options with if.
* Making multiple choices with cond.
* Lab!
* Reflection tomorrow.


==Choosing between two options with if==

Format
 (if test 
     consequent 
     alternative)

* consequent is only evaluated if test is truish
* alternative is only evaluated if test is #f
* alternative is not nececessary
* By convention, we put the test, alternative, and consequent all on
  separate lines

==Making multiple choices with cond==

Format
  (cond (test 
         consequents)
        (test 
         consequents)
        ...
        (else 
         alternative))

==Lab!==

* Reflection tomorrow.