1. Computer Programming TCP1224 Chapter 8 More On Repetition Structure

2. Repetitive structures while and for loops Pre-test loops Exercises that includes earlier lectures 2

3. Objectives Include the posttest repetition structure in pseudocode Include the posttest repetition structure in a flowchart Code a posttest loop using the C++ do while statement Nest repetition structures 3

4. Posttest Loops Loops can be pretest or posttest Condition in a posttest loop is evaluated with each loop iteration ▫Evaluation occurs after instructions within loop are processed  Also called bottom-driven loops 4

5. Posttest Loops (continued) 5

6. Flowcharting a Posttest Loop Flowcharts illustrate why loops are referred to as pretest and posttest loops ▫Repetition diamond appears at the top of a pretest loop, but at the bottom of a posttest loop 6

7. Flowcharting a Pre-test Loop 7

8. Flowcharting a Posttest Loop 8

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10. Coding the Posttest Loop Use the while statement or the for statement to code a pretest loop in C++ Use the do while statement to code a posttest loop in C++ ▫The loop condition must be a Boolean expression  Can contain variables, constants, functions, and arithmetic/comparison/logical operators 10

11. Coding the Posttest Loop 11

12. Posttest Loop Example Problem description ▫In January of each year, O’Donnell Incorporated pays a 10% bonus to each of its salespeople ▫Bonus based on amount of sales made by salesperson during previous year ▫Payroll clerk wants a program that calculates and displays each salesperson’s bonus amount 12

13. Posttest Loop Example 13

14. Posttest Loop Example 14

15. Post-test in C++ do { // statements } while ( ); 15

16. Nested Repetition Structures In a nested repetition structure, one loop (inner loop) is placed entirely within another loop (outer loop) 16

17. Nested Repetition Structures 17

18. Nested Loop Example Max Beauty Supply divides its sales territory into two regions: Region 1 and Region 2 Sales manager wants a program to enter the sales amounts for both regions, one region at a time ▫Program should calculate the total amount sold in the current region, and display that information 18

19. Nested Loop Example 19

20. Nested Loop Example 20

21. Nested Loop Example 21

22. Nested Loop Example 22

23. Multiple level nesting while ( ) { // statements for ( ; ; ) { // statements do { // statements } while ( ); } 23

24. Summary A repetition structure can be a pretest or posttest loop ▫In a pretest loop, the loop condition is evaluated before the instructions in the loop body are processed  Instructions may never be processed  Use while or for statements ▫In a posttest loop, the loop condition is evaluated after the instructions in the loop body are processed  Instructions are always processed at least once  Use the do while statement You can nest repetition structures 24