COMP 14 002 Intro to Computer Programming

1
COMP 14 (002)Intro to Computer Programming

• Instructor Todd Gamblin
• MW 11-1215
• F 11-1150
• Peabody 218

2
About Me

• 3rd year Ph.D. student, UNC Computer Science
• Work with RENCI
• Research interests
• Supercomputing
• Scalability
• Really big computers
• e.g. BlueGene, at left, is 132,000 computers put
  together

3
About Me Before UNC

• Undergrad
• Williams College
• Double major
• Computer Science, Japanese
• Swam (200 Backstroke, 400 IM)
• Worked for a year at a dot com
• Small company in Tokyo
• Java Programmer
• Yeah, this was my job
• Built interactive websites
• Affiliate marketing (a.k.a. ads)
• Web hosting (websites for building websites)

4
Why learn about computer science?

• Computers are pervasive
• Understanding programming will help you
  understand what they can and cannot do
• Computers are important tools
• You can write programs to solve large and/or
  tedious problems
• Lots of things are programmable (e.g.
  spreadsheets)
• Builds analytical problem-solving skills

5
About the course

• This is a course on programming
• Learn how to develop simple algorithms
• Learn structured, object-oriented design
• Is this course right for you?
• Have you programmed before?
• You should know how to download files and install
  programs
• I assume no prior programming knowledge
• Ask me about COMP 4 or COMP 14 if you have doubts

6
About the course

• You need to be enrolled in this course
• COMP 14 002
• And this recitation
• COMP 14 602
• I put some of you in the right recitation myself.
  I think these are synched up now, but make sure!

7
Textbook

• Java An Eventful Approach
• By Bruce, Danyluk, Murtagh
• Yeah, theyre all from Williams.
• Theres just one text, despite what they tell you
  at the book store
• Books were mislabeled
• Hope you got the right one
• Get it at UNC or Amazon

8
Software

• Programs we write will be in Java
• But you shouldnt focus on that
• Concepts from Java can be used in lots of
  languages (C, C, Python, Perl, etc, etc)
• Well be using IBMs Eclipse IDE
• IDE Interactive Development Environment
• This is a program for writing programs
• Helps you write Java
• This is what they use in the real world

9
Grades

• 20 Programming Assignments
• 40 Test Programs
• 15 Midterm
• 20 Final Exam
• 5 class participation and effort
• Im not taking attendance, but I will notice if
  you speak up

10
Format

• Programming assignments are approximately weekly
• Well start these in class
• These will be the bulk of the work you do
• These will also be where you learn the most
• Best way to learn programming is practice
• 2 Test programs
• These are basically big weekly assignments
• You do these all on your own
• Midterm in class
• Final after end of classes

11
Honor Code

• I handed out a sheet of guidelines
• Please sign this and get it back to me ASAP
• You could even turn it in today
• The Guidelines (abridged)
• You can work with other people on weekly
  assignments
• You cant copy code, but you can talk about how
  to do them
• You cant work with anyone on test programs
• You may use class materials (notes, text,
  previous assignments)
• Exams should also be all your own work
• These are in class, scheduled
• No notes, books, etc.

12
Late Assignments

• Assignments are due by 3am the night before the
  due date
• Turn them in online
• Date will be recorded
• You can resubmit, but Ill take the latest date
• Can turn in late for up to 24 hrs
• After that, the assignment is considered failed
• 15 late penalty

13
Course Webpage

• http//wwwx.cs.unc.edu/tgamblin/comp14

14
Course Webpage

• This is a Wiki!
• Whats that?
• You can edit and discuss course pages and
  assignments online
• Please log in and make an account (well do this
  Friday)

15
Course Webpage

• All assignments will be submitted on the Wiki

Then just select your homework and upload it!
First click here
Pretty simple, huh?
16
So whats computing about?

• Used to be about numbers and performing
  calculations
• That huge thing to the left is ENIAC
• Electronic Numerical Integrator and Computer
• Calculated ballistics trajectories during WWII
• First fully programmable machine

17
So whats computing about?

• These days, we need to manipulate all kinds of
  information
• Numbers
• Text
• Images
• Sound
• How do you make a computer understand these
  things?

18
So whats computing about?

• We need
• Clever ways to represent information in a
  computer
• Data structures
• Well build some simple ones
• Algorithms to manipulate them correctly and
  efficiently
• Whats an algorithm?

19
Algorithms

• Algorithm
• A series of instructions to be followed to solve
  some problem
• Think of a program as one type of algorithm
• series of instructions in software that controls
  the operation of a machine
• We want to design algorithms that are
• Correct Does the right thing actually solves
  the problem
• Efficient Solves the problem fast and doesnt
  use too many resources (e.g. too much memory)
• Understandable Humans can read and understand
  easily

20
Algorithms

• Designing good algorithms is difficult
• Dont believe me?
• Consider
• How common bad instructions are
• Ever been given the wrong directions?
• Computers are really dumb
• They do exactly what you say
• They cant figure out what you actually meant,
  whereas people can

21
Algorithms

• Lets try making an algorithm
• Give me directions from here to Starbucks
• Now give a robot the same directions
• How are they different?
• How detailed do they need to be?
• Are your instructions the same every time?
• What if theres construction?
• What about traffic?
• This can get pretty complicated

22
Writing good code

• When you write a program, it should be readable
  by a human
• Most real programs are constantly changing
• Most likely, someone other than you will need to
  understand what your code does
• Make it easy for them!
• Part of your grade on coding assignments will be
  for clarity and elegance
• More on this when we actually write code

23
Object-oriented programs

• Programs we design will be object-oriented
• Well model the world as objects
• Objects you build will respond to messages
• Suppose we wrote a program for the robot
• Build an object to represent the robot
• Design it so we can tell this object to walk,
  turn right, turn left, back up, stop
• Might even get more specific
• Robot object can be made of others
• Arm object, leg object, head object, body object
• Can send them messages
• Tell leg to lift
• Tell leg to move forward
• Tell leg to lower

24
Events

• Some of the programs we write will be
  event-driven
• Respond to events
• E.g. When the mouse clicks, do this
• Mouse click is the event
• do this is the action to take
• Robot might generate events
• E.g. Im out of battery!
• Battery exhaustion is the event
• We could write a program that responds to this
  event by telling the robot to go recharge himself
• Model Were notified of an event, and we write a
  program that describes how to respond

25
Concurrency

• Events in our programs can happen at the same
  time
• The mouse might be clicked and a key might be
  pressed at the same time
• The actions that respond to these events will
  occur at the same time
• Programming is moving more and more towards this
  mode of thinking!
• Remember my research? Those big computers can
  and do have 132,000 things going on at the same
  time
• Your computers can browse the web, play music,
  and check email all at once.
• For this course, well stick to very simple
  concurrency
• Our concurrent tasks wont interact w/each other

26
Some advice

• Writing programs can take some time
• Youll need to test things to make sure they work
• Youll know if things arent working
• This can be really maddening
• Start assignments early!
• There will almost always be bugs in code you
  write
• Its never a good feeling to turn in something
  that doesnt work, but its not the end of the
  world
• Turning in partially working code is always
  better than cheating

27
How to get help

• Talk to me after class, during office hours, or
  by appointment
• Office hours are TBA, will be posted on website
• Will be held in Sitterson 312 (thats just across
  the parking lot)
• Email me
• tgamblin_at_cs.unc.edu
• Call me at 919 360 8283

28
Feedback

• Email me with questions or comments on the course
  (tgamblin_at_cs.unc.edu)
• Use the webpage!
• Every assignment has a discussion section
• You can post comments and questions there, and
  Ill try to respond.
• Your classmates can, too, if I dont get to it
  before they do.

29
Questions?

• Homework
• Assignment 0 has been posted
• Read it, do it, and turn in the written part via
  the webpage
• Get me those signed honor code guidelines
  (turning them in now would be great, too)
• This Friday Recitation
• Bring your laptops
• Well do most of Assignment 0
• Well download Java and Eclipse (if you didnt
  yet)
• Register on the Wiki
• Well talk about how to use Eclipse and maybe
  write some really simple programs