p23 error
p1. stop watch
p19.Tax (polymorphism)
p2. account undo
p20. save
p24. CA
p3. DbCommand,DdConnection
p11. Stock Broker
4. Flow Chart Traversal , Pipes and Filter
5. Rule Engine
6. Invoice TaxType
7. AccountType - multi dimension
8. Stack, List, Queue
9. SADlg, CADlg, SADao,CADao
10. Account Enrichment
12. JobHandler
13. GameObject
14. Extendable Family
15. Log library
16. Statemachine
17. clone
18. student course
21.encryption 22. vehicle
Vertical and Horizontal: Two Approaches to the Decorator Pattern