1. CompSci 105 SS 2005 Principles of Computer Science Lecture 4 Lecturer: Santokh Singh

2. Parity Abstraction Modular Design Procedural Abstraction Data Abstraction Abstract Data Types Information Hiding Software Life Cycle Basic Stages Specification and Design Verification via Loop Invariants Costs Associated with Software

3. Hacking Type in a heap of code

4. Hacking Type in a heap of code Battle compilation errors

5. Hacking Type in a heap of code Battle compilation errors Run the code

6. Hacking Type in a heap of code Battle compilation errors Run the code If doesn’t work, change a random thing

7. Software Engineering Large Projects Team Development Guaranteed Results Easy Modification

8. Abstractions Complex Object Idealised Model Ignore Inessential Details

9. Class Reps Namelogin First meeting today/tomorrow (..)..time Place (CompSci …)

10. Parity Abstraction Modular Design Procedural Abstraction Data Abstraction Abstract Data Types Information Hiding Software Life Cycle Basic Stages Specification and Design Verification via Loop Invariants Costs Associated with Software

11. Modular (Class) Design System SecretCodes String Random

12. Procedural (Method) Design Encode SecretCodes Main Decode

13. Information Hiding Program that uses the String Class Implementation of the String Class API for the String Class

14. Data Abstraction int x = 14; 1110 14

15. Software Life Cycle Specification Design Verify Code Test Refine Produce Maintain

16. Software Life Cycle Specification Design Verify Code Test Refine Produce Maintain

17. Agreeing on a method Suppose we want a method that adds two integers uses the add method implements the add method

18. What needs to be specified? Suppose we want a method that adds two integers public int add ( int x, int y )

19. What needs to be specified? Suppose we want a method that adds two integers // General Description: // Precondition: // Postcondition: public int add ( int x, int y )

20. Course Book We have been referring to the Course Book during lectures:- Pages 62 - 64: Numbers in the Computer Pages 65 - 92: Data Representations Please attend ALL classes for better understanding & for your own good.