1. COS 121 - Sept 9, 2005 Key Issues in Programming Stefan Brandle

2. Agenda Visitor: David Orme, TU grad of ‘91. Introduce Autograder system Lab 1 questions Key issues in programming (Ch 1.3) Quiz 1

3. Visit: David Orme Mr. Orme will be speaking about a topic of his choice that is sure to inspire you. :-) Seriously, if you are willing to listen and learn from people who have gone through before you, you will be greatly rewarded. Ask questions. E.g., “Are our jobs really all going to India and China?”

4. Introduction to Autograder www.css.taylor.edu/~autograder/php Go through quick demo Hand out login info

5. Lab 1 Questions Any questions? Now would be a good time to ask. You also will have a chance to ask lab 1 questions on Monday

6. Key Issues in Programming Modularity Modifiability Ease of use Fail-safe programming Style Debugging

7. Modularity Programming tasks get harder as size and complexity increase Modularity slows the rate at which difficulty increases Specifically helps with: –Constructing the program –Debugging the program –Reading the program –Modifying the program –Eliminating redundant code

8. Modifiability Want to make programs easy to modify Functions Named constants The “typedef” statement

9. Ease of Use Always prompt user so that user knows what is expected Always echo back input Output should be well labeled and easy to read

10. Fail-Safe Programming A fail-safe program will perform reasonably no matter how anyone uses it. That goal is not attainable. Next best is: Deal with errors in input data: do not acccept bad data Check for logic errors: program monitors itself and self-reports problems Throwing exceptions

11. Style Extensive use of functions Use of private data members Avoidance of global variables in functions Proper use of reference arguments Proper use of functions Error handling Readability Documentation

12. Debugging Learn to use a good debugger Systematically check program logic to figure out where the error occurs: there is always an explanation, nothing is random Create functions to dump data

13. Quiz Woo-hoo!