1. 16.216 ECE Application Programming
Instructor: Dr. Michael Geiger
Summer 2015
Lecture 1:
Course overview
Basic C program structure
Data: constants and variables

2. ECE Application Programming: Lecture 1
Lecture outline
Announcements
Program 1 due 5/22
40 points: complete simple C program
10 points: introduce yourself
If we’ve met previously, you still have to meet with me this semester to earn these points.
Course overview
Instructor information
Course materials
Course policies
Resources
Course outline
Introduction to C programming
Program development cycle
Development environments
Basic program structure
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ECE Application Programming: Lecture 1

3. Course staff & meeting times
Lectures:
TTh, 9 AM-12 PM, Ball 412
F (5/29 & 6/12 only) 9 AM-12 PM, Ball 412
Instructor: Dr. Michael Geiger
Phone: (x43618 on campus)
Office: 118A Perry Hall
Office hours: T/Th 12-1 or by appointment
Only on campus days we have class (T/Th + F 5/29, 6/12)
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ECE Application Programming: Lecture 1

4. ECE Application Programming: Lecture 1
Course materials
Textbook: K.N. King, C Programming: A Modern Approach, 2nd edition, 2008, W.W. Norton.
ISBN:
Course tools: Need integrated development environment (IDE) that compiles/runs C code
Recommended IDEs (all free; links on web)
Windows: Microsoft Visual Studio Express (MS website)
Mac: Xcode (Mac App Store)
Linux: gcc/gdb (text-based; can run through terminal on Mac as well)
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ECE Application Programming: Lecture 1

5. Additional course materials
Course websites:
Will contain lecture slides, handouts, assignments
Discussion group through piazza.com:
Allow common questions to be answered for everyone
All course announcements will be posted here
Will use as class mailing list—please enroll ASAP
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ECE Application Programming: Lecture 1

6. ECE Application Programming: Lecture 1
Course policies
Academic honesty
All assignments are to be done individually unless explicitly specified otherwise by the instructor
Any copied solutions, whether from another student or an outside source, are subject to penalty
You may discuss general topics or help one another with specific errors, but do not share assignment solutions
Must acknowledge assistance from classmate in submission
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ECE Application Programming: Lecture 1

7. Programming assignments
Will submit all code via to Dr. Geiger
Will not get confirmation unless you explicitly ask
Penalty after due date: -(4n-1) points per day
i.e., -1 after 1 day, -4 after 2 days, -16 after 3 days …
Assignments that are 4+ days late receive 0
See grading policies (last three pages of today’s handout) for more details on:
Grading rubric
Common deductions
Regrade policy
Example grading
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ECE Application Programming: Lecture 1

8. Programming assignments: regrades
You are allowed one penalty-free resubmission per assignment
Each regrade after the first: 1 day late penalty
Must resubmit by regrade deadline, or late penalties will apply
Late penalty still applies if original submission late
“Original submission”  first file submitted containing significant amount of relevant code
In other words, don’t turn in a virtually empty file just to avoid late penalties—it won’t count
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ECE Application Programming: Lecture 1

9. ECE Application Programming: Lecture 1
Grading and exam dates
Grading breakdown
Programming assignments: 60%
Exam 1: 10%
Exam 2: 15%
Exam 3: 15%
Exam dates
Exam 1: Friday, May 29
Exam 2: Thursday, June 11
Exam 3: Thursday, June 25
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ECE Application Programming: Lecture 1

10. Tentative course outline
Basic C program structure and development
Working with data: data types, variables, operators, expressions
Basic console input/output
Control flow
Functions: basic modular programming, argument passing
Pointers, arrays, and strings
File & general input/output
Bitwise operators
Creating new data types: structures
Dynamic memory allocation
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ECE Application Programming: Lecture 1

11. Programming exercises
Note on course schedule: several days marked as “PE#”
Those classes will contain supervised, in-class programming exercises
We’ll write/complete short programs to illustrate previously covered concepts
If you have a laptop, bring it
May have to do some design ahead of time
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ECE Application Programming: Lecture 1

12. ECE Application Programming: Lecture 1
Course questions
General notes/questions about the course:
How many of you have prior programming experience?
For those that do, can improve programming style, efficiency, potentially learn new items
For those that don’t, course assumes no prior programming experience
Fair warning for all of you: material builds on itself throughout course
Difficulty increases as course goes on
If (when) you get stuck, ask for help!!!
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ECE Application Programming: Lecture 1

13. Course questions (continued)
How many of you are taking this course only because it’s required?
Follow-up: how many of you hope you’ll never have to program again once you’re done with the course?
Both computer and electrical engineers commonly program in industry—some examples:
Automation of tasks
Circuit simulation
Test procedures
Programming skills highly sought by employers
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ECE Application Programming: Lecture 1

14. ECE Application Programming: Lecture 1
Program development
... which is a good approach for your assignments, too!
Average student’s approach to programming
Read specification (assignment)
... at least some of it, anyway ...
Attempt to write complete program
Find output error and fix related code
Repeat previous step until either
Code completely works ...
... or code is such a mess that problem(s) can’t be fixed
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ECE Application Programming: Lecture 1

15. Program development (cont.)
A more structured approach to program development
Read specification
Identify requirements
What results should program produce?
How can I test correctness of those results?
Plan design that implements requirements
Using flowchart, pseudocode, etc.
Plan for tests as well
Translate design into actual code
Test program and fix errors
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ECE Application Programming: Lecture 1

16. ECE Application Programming: Lecture 1
Our first C program
#include <stdio.h> int main() { printf("Hello World!\n"); return 0; }
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ECE Application Programming: Lecture 1

17. ECE Application Programming: Lecture 1
Our first C program
# indicates pre-processor directive
include is the directive
stdio.h is the name of the file to "insert" into our program. The <> means it is part of the C development system
#include <stdio.h> int main() { printf("Hello World!\n"); return 0; }
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ECE Application Programming: Lecture 1

18. ECE Application Programming: Lecture 1
Our first C program
main is the name of the primary (or main) procedure. All ANSI C programs must have a main routine named main
The () indicates that main is the name of a procedure. All procedure references must be followed with ()
#include <stdio.h> int main() { printf("Hello World!\n"); return 0; }
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ECE Application Programming: Lecture 1

19. ECE Application Programming: Lecture 1
Our first C program
{ } enclose a "block". A block is zero or more C statements. Note that code inside a block is typically indented for readability—knowing what code is inside the current block is quite useful.
#include <stdio.h> int main() { printf("Hello World!\n"); return 0; }
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ECE Application Programming: Lecture 1

20. ECE Application Programming: Lecture 1
Our first C program
printf() is a "built-in" function (which is actually defined in stdio.h).
"Hello World!" is the string to print. More formally, this is called the control string or control specifier.
#include <stdio.h> int main() { printf("Hello World!\n"); return 0; }
Every statement must end with a ";". Preprocessing directives do not end with a ";" (but must end with a return).
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ECE Application Programming: Lecture 1

21. ECE Application Programming: Lecture 1
Our first C program
The \n is an escape character used by the printf function; inserting this character in the control string causes a “newline” to be printed—it’s as if you hit the “Enter” key
#include <stdio.h> int main() { printf("Hello World!\n"); return 0; }
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ECE Application Programming: Lecture 1

22. ECE Application Programming: Lecture 1
Our first C program
The int tells the compiler our main() program will return an integer to the operating system; the return tells what integer value to return. This keyword could be void, indicating that the program returns nothing to the OS.
#include <stdio.h> int main() { printf("Hello World!\n"); return 0; }
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ECE Application Programming: Lecture 1

23. Variations #1 of first program
#include <stdio.h> int main() { printf("Hello"); printf("there"); printf("World!"); return 0; }
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24. Variations #2 of first program
#include <stdio.h> int main() { printf("Hello\n"); printf("there\n"); printf("World!\n"); return 0; }
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ECE Application Programming: Lecture 1

25. Variations #3 of first program
#include <stdio.h> int main() { printf("Hello\nthere\nWorld!\n"); return 0; }
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26. Variations #4 of first program
#include <stdio.h> int main(){printf ("Hello\nthere\nWorld!\n");return 0;}
Note while this is syntactically correct, it leaves much to be desired in terms of readability.
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ECE Application Programming: Lecture 1

27. ECE Application Programming: Lecture 2
Code readability
Readability wouldn’t matter if:
Entire code project written by one person
All code was in same file
Same person is the only one to use the code
Code was used only for a short period of time
More typically:
Projects are split—multiple programmers and files
Code usually reused
Multiple users
Used/adapted (hopefully) over long period of time
You may reuse code ... but forget what you originally wrote!
Bottom line: code needs to be readable
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ECE Application Programming: Lecture 2

28. ECE Application Programming: Lecture 2
Comments
C allows you to add comments to your code
Single line comments: start with //
Multi-line comments: start with /*
end with */
Typical uses
Multi-line comment at start of program with
Author’s name (& other info if appropriate)
Date started/modified
File name
Description of overall file functionality
For individual code sections
Single/multi-line comment for major section of code performing single function
Single line comment for single line of code if that line alone is important
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ECE Application Programming: Lecture 2

29. ECE Application Programming: Lecture 2
Comment example
/* ECE Application Programming Instructor: M. Geiger 6/12/2018 hello.c: Intro program to demonstrate basic C program structure and output */ #include <stdio.h> // Main program: prints basic string and exits int main() { printf("Hello World!\n"); // Comment return 0; }
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ECE Application Programming: Lecture 2

30. ECE Application Programming: Lecture 2
Representing data in C
Two major questions (for now)
What kind of data are we trying to represent?
Data types
Can the program change the data?
Constants vs. variables
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ECE Application Programming: Lecture 2

31. Four Types of Basic Data
Integer int
Floating point (single precision) float
Double Precision double
Character char
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ECE Application Programming: Lecture 2

32. ECE Application Programming: Lecture 2
Integer Constants
Any positive or negative number without a decimal point (or other illegal symbol).
Legal values:
Illegal values: 2,523 (comma) 6.5 (decimal point) $59 (dollar sign) 5. (decimal point)
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ECE Application Programming: Lecture 2

33. Range of Integers (Machine Dependent)
unsigned signed
char 0   +127
(8 bits)
short int 0   short
(16 bits)
int 0 to  long long int
(32 bits)
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ECE Application Programming: Lecture 2

34. float/double Constants
Any signed or unsigned number with a decimal point
Legal values:
Legal (exponential notation): 1.624e e e23 1.0e e e e e+7
Illegal:
$ , E5
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ECE Application Programming: Lecture 2

35. float/double Constants
Range of float (32 bits) ± E – 38 ± E + 38
Range of double (64 bits) ± E – 308 ± E + 308
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ECE Application Programming: Lecture 2

36. ECE Application Programming: Lecture 2
Character Constants
Stored in ASCII or UNICODE
Signified by single quotes (’ ’)
Valid character constants ’A’ ’B’ ’d’ ’z’ ’1’ ’2’ ’!’ ’+’ ’>’ ’?’ ’ ’ ’#’
Invalid character constants ’GEIGER’ ’\’ ’CR’ ’LF’ ’’’ ’’’’ ’”’ ”Q”
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ECE Application Programming: Lecture 2

37. Character Escape Sequences
Meaning
’\b’
Backspace
’\’’
Single quote
’\n’
Newline
’\”’
Double quote
’\t’
Tab
’\nnn’
Char with octal value nnn
’\\’
Backslash
’\xnn’
Char with hex value nn
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ECE Application Programming: Lecture 2

38. Using #define with constants
Often makes sense to give constant value a symbolic name for readability
Don’t want constant wasting memory space
Use #define to define a macro
Macro: named code fragment; when name is used, the preprocessor replaces name with code
Syntax: #define <name> <code>
Common use: defining constants
By convention, start constant values with capital letters
e.g. #define NumberOne 1
At compile time, all uses of “NumberOne” in your program are replaced with “1” and then compiled
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ECE Application Programming: Lecture 2

39. ECE Application Programming: Lecture 2
Variables
All variables have four characteristics:
A type
An address (in memory)
A value
A name
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ECE Application Programming: Lecture 2

40. ECE Application Programming: Lecture 2
Variables - name
must start with a-z, A-Z ( _ allowed, but not recommended)
other characters may be a-z, A-Z, 0-9, _
upper case/lower case are not equal (i.e. ECE, ece, Ece, EcE, eCe would be five different variables)
max length system dependent (usually at least 32)
By convention
Start with lowercase letter
Descriptive names improve code readability
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ECE Application Programming: Lecture 2

41. Variables - legal names
grossPay
carpet_Price
cArPeT_price
a_very_long_variable_name i
______strange___one_____
_ (not recommended)
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ECE Application Programming: Lecture 2

42. Variables - legal names (but not recommended)
l (that's lower case L)
O (that's capital O)
l1 (that's lower case L, and digit one)
O0Oll11 (oh,zero,oh,el,el,one,one)
_var (many system variables begin w/ _ )
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ECE Application Programming: Lecture 2

43. ECE Application Programming: Lecture 2
Variables - declaring
var name
memory loc
main() { float hours, payrate; float grosspay; int j;
hours ?
4278
payrate ?
427C
4280
grosspay ? j ?
4284
All variable declarations should be grouped together at the start of the function
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ECE Application Programming: Lecture 2

44. ECE Application Programming: Lecture 2
Variables - assigning
varname = expression;
Declared variable
single variable on left side of =
expression
any legal expression
Expression can be constant, variable, function call, arithmetic operation, etc.
Variable type (int, float, etc) and expression result type should match
If not, funny things can happen ...
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ECE Application Programming: Lecture 2

45. ECE Application Programming: Lecture 2
Variables (cont.)
var name
memory loc
main() { float hours, payrate; float grosspay; int j;
hours = 40.0;
hours
40.0
4278
payrate ?
427C
4280
grosspay ? j ?
4284
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ECE Application Programming: Lecture 2

46. ECE Application Programming: Lecture 2
Variables (cont.)
var name
memory loc
main() { float hours, payrate; float grosspay; int j;
hours = 40.0;
payrate = 20.00;
hours
40.0
4278
payrate
20.0
427C
4280
grosspay ? j ?
4284
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ECE Application Programming: Lecture 2

47. ECE Application Programming: Lecture 2
Variables (cont.)
var name
memory loc
main() { float hours, payrate; float grosspay; int j;
hours = 40.0;
payrate = 20.00;
grosspay = hours * payrate;
hours
40.0
4278
payrate
20.0
427C
4280
grosspay
800.00 j ?
4284
note: referencing a variable only "reads" it (non-destructive). Assigning to a variable overwrites whatever was there (destructive).
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ECE Application Programming: Lecture 2

48. ECE Application Programming: Lecture 2
Variables (cont.)
var name
memory loc
main() { float hours, payrate; float grosspay; int j;
hours = 40.0;
payrate = 20.00;
grosspay = hours * payrate;
j = 5;
hours
40.0
4278
payrate
20.0
427C
4280
grosspay
800.00 j 5
4284
note: referencing a variable only "reads" it (non-destructive). Assigning to a variable overwrites whatever was there (destructive).
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ECE Application Programming: Lecture 2

49. ECE 160 - Introduction to Computer Engineering I
02/09/2005
Variables (cont.)
var name
memory loc
main() { float hours, payrate; float grosspay; int j;
hours = 40.0;
payrate = 20.00;
grosspay = hours * payrate
j = 5;
j = j + 1;
hours
40.0
4278
payrate
20.0
427C
4280
grosspay
800.00 j
5 6
4284
note: referencing a variable only "reads" it (non-destructive). Assigning to a variable overwrites whatever was there (destructive).
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ECE Application Programming: Lecture 2
(c) 2005, P. H. Viall

50. ECE Application Programming: Lecture 3
Example: Variables
What values do w, x, y, and z have at the end of this program?
int main() {
int w = 5;
float x;
double y;
char z = ‘a’;
x = 8.579;
y = -0.2;
w = x;
y = y + 3;
z = w – 5;
return 0; }
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ECE Application Programming: Lecture 3

51. ECE Application Programming: Lecture 3
Example solution
int main() {
int w = 5;
float x;
double y;
char z = ‘a’;
x = 8.579;
y = -0.2;
w = x;
y = y + 3;
z = w – 5;
return 0; }
w = 5
z = ‘a’ (ASCII value 97)
x = 8.579
y = -0.2
w = 8 (value is truncated)
y = (-0.2) + 3 = 2.8
z = 8 – 5 = 3
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ECE Application Programming: Lecture 3

52. ECE Application Programming: Lecture 2
Assignment #1
Basic assignment to ensure you can write, run, and submit programs
Write a short program that prints (each item on its own line):
Your name
Your major
Your class (i.e. freshman, sophomore, etc.)
The name and semester of this course
Submit only your source (prog1_simple.c) file via to
File name matters!
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ECE Application Programming: Lecture 2

53. ECE Application Programming: Lecture 1
Final notes
Next time:
Operators
Basic input/output with scanf()/printf()
PE1: Flowcharts and debugging basics
Reminders:
Sign up for the course discussion group on Piazza!
Program 1 due Friday, 5/22
40 points: complete simple C program
10 points: introduce yourself If we’ve met previously, you still have to meet with me this semester to earn these points.
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ECE Application Programming: Lecture 1