1. EECE.2160 ECE Application Programming
Instructors:
Dr. Michael Geiger & Peilong Li
Spring 2016
Lecture 2:
Basic C program structure
Data in C: Data types, constants, and variables

2. ECE Application Programming: Lecture 2
Lecture outline
Announcements/reminders
Sign up for the course discussion group
Program 1 due Wednesday, 1/27
10 points: Dr. Geiger for shared Dropbox folder
10 points: introduce yourself to your instructor
30 points: complete simple C program
Today’s lecture
Basic C program structure
Comments
Data types
Constants
Visual Studio demo
4/30/2019
ECE Application Programming: Lecture 2

3. ECE Application Programming: Lecture 1
Our first C program
#include <stdio.h> int main() { printf("Hello World!\n"); return 0; }
4/30/2019
ECE Application Programming: Lecture 1

4. 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; }
4/30/2019
ECE Application Programming: Lecture 1

5. 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; }
4/30/2019
ECE Application Programming: Lecture 1

6. 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; }
4/30/2019
ECE Application Programming: Lecture 1

7. 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).
4/30/2019
ECE Application Programming: Lecture 1

8. 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; }
4/30/2019
ECE Application Programming: Lecture 1

9. 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; }
4/30/2019
ECE Application Programming: Lecture 1

10. Variations #1 of first program
#include <stdio.h> int main() { printf("Hello"); printf("there"); printf("World!"); return 0; }
4/30/2019
ECE Application Programming: Lecture 1

11. Variations #2 of first program
#include <stdio.h> int main() { printf("Hello\n"); printf("there\n"); printf("World!\n"); return 0; }
4/30/2019
ECE Application Programming: Lecture 1

12. Variations #3 of first program
#include <stdio.h> int main() { printf("Hello\nthere\nWorld!\n"); return 0; }
4/30/2019
ECE Application Programming: Lecture 1

13. 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.
4/30/2019
ECE Application Programming: Lecture 1

14. 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
4/30/2019
ECE Application Programming: Lecture 2

15. 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
4/30/2019
ECE Application Programming: Lecture 2

16. ECE Application Programming: Lecture 2
Comment example
/* ECE Application Programming Instructor: M. Geiger 4/30/2019 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; }
4/30/2019
ECE Application Programming: Lecture 2

17. 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
4/30/2019
ECE Application Programming: Lecture 2

18. 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

19. 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)
4/30/2019
ECE Application Programming: Lecture 2

20. 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)
4/30/2019
ECE Application Programming: Lecture 2

21. 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
4/30/2019
ECE Application Programming: Lecture 2

22. float/double Constants
Range of float (32 bits) ± E – 38 ± E + 38
Range of double (64 bits) ± E – 308 ± E + 308
4/30/2019
ECE Application Programming: Lecture 2

23. 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 to your Dropbox folder
File name matters!
4/30/2019
ECE Application Programming: Lecture 2

24. ECE Application Programming: Lecture 2
Visual Studio demo
Basics of setting up project
Steps covered in detail in Program 1 spec.
Xcode users: steps are very similar
Choose “Start New Project” when Xcode opens
Project type:
Under list of “OS X” choices on the left, choose “Application”
Choose “Command Line Tool” from the options that appear
Name your project (project name doesn’t matter) and choose a directory. Also, ensure that the type of project is set to “C” using appropriate drop-down menu
Project includes simple C file named “main.c”
You can edit this file to include your own code
Rename this file so the name matches the program spec
4/30/2019
ECE Application Programming: Lecture 2

25. ECE Application Programming: Lecture 2
Final notes
Next time
Variables
Operators
Basic output with printf()
Reminders:
Sign up for the course discussion group
Program 1 due Wednesday, 1/27
10 points: Dr. Geiger for shared Dropbox folder
10 points: introduce yourself to your instructor
30 points: complete simple C program
4/30/2019
ECE Application Programming: Lecture 2