CS100J, Fall 2001
Thurs 9/20
Lecture 7
-------------------------------------------------------------------------------
Announcements:
+ Thanks Mike!
+ new? responsible for www.cs.cornell.edu/Courses/cs100j/2001fa/
  start with Overview and Grading-->Adding
+ reading next week: Chap 4.1, Chap 5.1-5.4 (9/25,9/27)
+ Next-Next week: All of Chap 4
+ TokenReader Mystery? see Java-->CUCS Files
+ section: 3rd attempt....
-------------------------------------------------------------------------------
Topics:
+ reminders from Tuesday
+ $while$
+ categories of loops
+ increment operators
-------------------------------------------------------------------------------
Reminders:
+ repetition statements
  - could do millions of $if$s, but why would you want that?
  - use $while$
+ syntax
  while(c) {
     s1;
     s2;
  }
+ variables in { }
  - { } indicates block statement
  - can declare var in block if not declared BEFORE the block
  - cannot redeclare *within the same* block, 
    but repetition statement allowed to use the same block
+ increment operators: ++, --, +=, *= (pp77-79)
  - used for shortcuts  
  - ++, --, +=, *=
    a++: postincrement
    ++a: preincrement
+ not allowing $for$, $do$-$while$ for "awhile" (forgive the pun)
+ $break$, $System.exit$
  - $break$: breaks out of loop
    $exit$: exits from program
  - avoid! generally interrupts control flow, which makes it hard to trace
+ other issues:
  - sentinel values: values to stop loop
  - named constants: initialize before loop to generalize code
+ generalizations of loops:
  (1) definite
      - repeat/echo (could use $for$ -- discussed later)
      - accumulate
  (2) indefinite
      - conditional update
+ built-in/imported methods (so far)
  - main
  - System.out.println()
  - equals (equalsIgnoreCase, and so forth)
  - SavitchIn.readInt (and so forth)
  - Math.sqrt, Math.pow, Math.max, Math.min (pp 316-318)
    Math.random (random.txt: online notes)
-------------------------------------------------------------------------------
How to Design Loops
- preprocessing
- looping
- postprocessing
-------------------------------------------------------------------------------