1. CSC 107 – Programming For Science

2. Today’s Goal  Know how to use and write for loops  Explain why to use for, while, & do-while loops  Convert between the 3 loops with same end result  Explain why we would never convert between loops

3. Loop Structure

4. while Loop while (expression) { statement;... } L OOP TERMINATION CONDITION  expression is L OOP TERMINATION CONDITION  Boolean expression checked at start of each pass  Executes entire loop body if expression is true  Once expression checked & found false, loop is over  L OOP BODY  L OOP BODY inside braces executed during pass

5. do-while Loop

6. Loop Structure

7. Loop Control Variant  Variable used to control when loop ends  Counting passes of loop often performed with this  Count not literal; could be constant form of update  Very common when used in strictly bounded loops

8. Loop Control Variant  Examples of loops using loop control variant  Launching a rocket (10-9-8-7-6-5-4-3-2-1-Blast off!)

9. Loop Control Variant  Examples of loops using loop control variant  Launching a rocket (10-9-8-7-6-5-4-3-2-1-Blast off!)  Going through even numbers (2-4-6-8…)

10. Loop Control Variant  Examples of loops using loop control variant  Launching a rocket (10-9-8-7-6-5-4-3-2-1-Blast off!)  Going through even numbers (2-4-6-8-10-12-14…)  Alarm clocks (5:57… 5:58… 5:59… $@#$@ it!)

11. Loop Control Variant  Examples of loops using loop control variant  Launching a rocket (10-9-8-7-6-5-4-3-2-1-Blast off!)  Going through even numbers (2-4-6-8-10-12-14…)  Alarm clocks (5:57… 5:58… 5:59… $@#$@ it!)  Love (She loves me, she love me not, she loves me)

12. for Loop

13. Initialization Expression

14. Loop Control Variant Update

15. Comparing for & while Loops for Loop while Loop

16. Tracing for Loop

19. Counting in for Loops  for 's control variant often counts up or down  Check against limit in loop termination expression  Limit against which we will check is often constant  Use constants to hold value of these limits  Makes code much easier to read  Simplifies changing code when limit needs to change for (i = 0; i < 42; i++) or for (i = 0; i < THE_ANSWER; i++)

20. Your Turn  Get in groups & work on following activity

21. For Next Lecture