APS105

1. APS105 Introduction

2. Welcome • To University and UofToronto • To Engineering • To APS105

3. About your Prof • Prof. Greg Steffan • PhD Computer Science, Carnegie Mellon, 2003 • BASc/MASc, ECE, UofToronto, 1995/1997 • Research • Making multicores and FPGAs easier to program • Contact: • steffan@eecg.toronto.edu • Office: EA321 • Office hours: wed 12-1pm

4. Why Learn About Programming and C?

5. Why Learn Programming? • Computers: our most powerful technology • Learn to command them to do your bidding! • For love of design • Programming is pure design with few limitations • “only slightly removed from pure thought-stuff” • Entrepreneurial opportunities • Start a company in your bedroom with no $$$ • Many engineering jobs involve programming • Simulations, databases, websites • Whether civil, electrical, mechanical…

6. Why Learn C? • Lots of other newer, sexier languages • Java, Python, Ruby, javascript • Benefits of C: • “Compiled language”, not “interpreted” • Close to the hardware with no layers between • Easier to understand what is happening • Important building-block for later computing courses • C/C++ still very common • In high-performance applications • In low-level code like operating systems, databases,… • C-like-syntax found in many of above languages

7. Why Attend Lectures? • To see someone else think through problems • Different than simply seeing the solution • Learn “why”, not just “how” • how course material fits in with “big picture” • Will provide proper emphasis • Highlight key material • Overview-only sundry material • Will teach material in order of importance • Eg., order that you need it for labs • Ideally more entertaining than reading manual • Else Prof-fail.

8. Administration

9. Course Website • Portal.utoronto.ca • APS105FALL 2011 • Any Handouts • Lab Assignments • Past Exams • Form for missed labs/quizzes • Form for misgraded midterm • Discussion Board

10. Course Meetings • Lecture Periods: • three one-hour lectures per week • Start at 10mins after the hour • Optional Lecture: • review of regular lecture material • attendance recommended for non-experts • tuesdays 3-4pm MC102 (entire course invited) • Tutorial Periods: • One per week, run by TAs • Quizes in about half of the tutorials • Attendance optional, unless there is a quiz • Lab Periods: • Two hours per week • TAs available to answer questions • Attendance "mandatory"

11. Evaluation • Quizzes: 8% • 4 total • Given in tutorials • Based on lecture material since last quiz • Labs: 17% • 8 total • Midterm: 25% • Final Exam: 50% • Emphasis on 2nd half of course

12. Lecture Slides and Note-Taking • Electronic slides with fill-in-the-blanks • A hybrid between powerpoint and chalkboard • Pptx/pdf available on www prior to lecture • Please print and bring to class • The filled-in “blanks” are only during class • Filled-in slides will not be published • The symbol that indicates a blank to fill

13. Course Textbook • “An Introduction to Computer Science Using C”, 2nd Edition • by John Carter • Published by McGraw Hill-Ryerson • How to get a copy: • UofT bookstore • basement of Sandford Fleming Building • Amazon etc.

14. Labs (programming assignments) • There are 8 of them in total • You will always be working on one • Must run properly on ECF systems • Even if it runs fine elsewhere • Marks for functionality and style • Proper style will be defined throughout term

15. Cheating/Copying • Easy to do, equally easy to catch! • “cheater-beater” software • Automatically compares all submissions • we do actually do this, and do follow through! • the interview and punishment process is painful for all! • You only cheat yourself • Labs worth 1.6% each • The practice you get by doing them is invaluable • The consequences for being caught are harsh • See Engineering Calendar for details

16. Getting Help • See course info handout • Meet some friends: “study groups” • Collaborating vs cheating • Ask questions in class • Point out confusing things and mistakes! • Get help quickly if you get into trouble • First-year office (1st floor Galbraith Building) • www.calss.utoronto.ca • Help with academics, personal

17. In-Class Etiquette • Be on time • Class starts at 10mins after the hour • Quiet please! • Silence yourself and all electronic devices! • Pay attention • Eg., watching youtube on laptop distracts others • Ask questions and point out errors! • Raise your hand • Say “question!” if I don’t notice

18. How to Succeed at APS105 • Attend lectures • take notes, ask questions • Do labs yourself, on-time • Practice/experience is invaluable • Review lecture material regularly • Be better prepared for quizes/midterm/final • Avoid last-minute cramming • Prepare for midterm/final • Practice by trying past midterms/finals • Practice by filling lecture slides on your own • Both available on www

19. How to Succeed at Skule (computing) • Learn to keyboard properly! • Learn unix/linux basics • see the unix handout • has details on how to log in from home • Learn some javascript • For programming www page features • Write a simple app for your own use • Eg., for your laptop or iphone

20. Computer Systems Basics

21. Computer Systems Stack

22. Programmer Compiler Machine Instructions Processor 0100101 Add r3,r3,r1 Cmp r3,r1 Bge 0x3340a Mulu r3,r5,r2 Sub r1,r3,r4 … How We Tell a Processor What to Do int Foo (int x){ return x + 5; } … Processors execute machine instructions encoded in binary

23. Monitor A TYPICAL PC Graphics card Motherboard (CPU, MEMORY) Hard drive CD/DVD R/W USB Connectors Keyboard Mouse Power Supply

24. CPU Memory (RAM) Simple View of a Motherboard • Memory: • holds bits • can be read from or written to • CPU: • datapath: arithmetic/logic units (add, sub), etc. • control circuitry

25. C

26. About C • Invented in Bell Labs (in 1970s) • by Dennis Ritchie • Inherits from earlier language • called “B” • C++ • an extension of C • Supports “object oriented programming” Dennis Ritchie

27. Hello World .

28. Alternative Hello World .

29. GCC • gcc • Means “GNU C compiler” • A program that converts C to 0’s & 1’s • Stored in a file called an “executable” • Type this command to compile hello.c • Generates the executable file • Insteady you could type: • Generates the executable file

30. Value Representation

31. Bits and Bytes • “bit” is short for “binary digit” • A bit can be 0 or 1 • Why do computers use bits? • A byte is a group of 8 bits • 1 byte can be written as 1B

32. RECALL: BASE 10 (decimal) • 956 • NOTE: not all languages/cultures use base10 • Ndom, FrederikHendrik Island: base6 • nimbia: base12 • Huli, Papua New Guinea: base15 • Tzotzil, Mexico: base20 • Computers use base2 (binary)

33. USING BINARY (BASE 2) • denoted by ‘0b’ (in this course, in C-code) • Converting from binary to decimal: • 0b1011

34. Questions • How many decimal numbers can you represent with N bits? • NOTE: • computers can only represent finite numbers!

35. Byte Size • 1byte = 1B = 8bits

36. What is this? 10010010

37. Types

38. Types • Data Type: • tells computer how to interpret a group of bits • Without a type they are just bits! • C has types: • Basic data types: built-in, already defined for you • User-defined types: name your own! (later) • Basic data types: • A single value of a certain size (bytes) • Example: a number or a character

39. Integer Types • int: 32bits, values: -231 .. 231-1 • We will almost always use int in this class • Other integer types: • unsigned int: 32bits, values 0.. 232-1 • short: at least 16bits • long: at least 32bits • long long: at least 64bits • what does "at least" mean? • the actual size can depend on the system!!!!!

40. Floating Point Types • How to use binary to represent real numbers? • Eg., 1.3333333333333…. • Can’t: approximate, with limited accuracy • Floating-point: a common approximation • A value (mantissa) and an exponent • Flexible: can represent very big or very small • Eg., 2.1313*1020 or 2.1313*10-20 • We don’t need to know the details for this class

41. Floating Point Types in C • double: at least 64 bits • We will almost always use double in this class • float: at least 32 bits

42. Character Type • representing keyboard characters: • Eg: a,b,c,d…A,B,C,D, !@#$% • Standard encoding called ASCII: • eg., ‘A’ = 65 = 0100 0001 (binary) • char: 8 bits, typically ASCII-encoded • Note1: char holds only a single character • How can we represent a “string” of characters? • Note2: recall “escapes” • Eg., ‘\n’ represents the return character • Encoded as a single ASCII value

43. Boolean Type • Often you want to represent true/false • The old way: use int values 0 and 1 • The new way: use the bool type • bool type • Has values ‘true’ and ‘false’ • Note: you have to include the bool library • in program (at top): #include <stdbool.h>

44. Identifiers and Variables

45. Identifiers • Identifiers give names to things • Choosing good names is a key skill! • Rules: identifiers can be • any length (any number of characters) • upper & lower case letters, digits, ‘_’ • First character cannot be a digit • Cannot match a C “reserved” word (like “int”)

46. Choosing Identifiers: Good Style • Use upper-case to separate words: • Or use underscores to separate words: • Avoid easily-confused characters: • Choosing good identifiers is an art:

47. Declaring Variables • Variable: storage of a value of a certain type • Variable declaration: • specifies that you plan to use a variable • and you would like it to be a certain type • Note: the C-compiler creates storage for it • General form: <type> <identifier list>;

48. Declaring Variables: Examples • Example declarations:

49. Assigning Values • Can assign a value at declaration, or later • Example assignment at declaration: • Example assignment at a later point: • Accuracy:

50. Output