EECE.2160 ECE Application Programming

1. EECE.2160ECE Application Programming Instructors: Dr. Michael Geiger & Dr. Peilong Li Spring 2017 Lecture 2: Basic C program structure Data in C: Data types, constants, and variables

2. Lecture outline • Announcements/reminders • Sign up for the course discussion group • Respond to poll re: TA office hours • Program 1 due Wednesday, 1/25 • 10 points: e-mail Dr. Geiger for shared Dropbox folder • Please specify e-mail address associated with Dropbox account • You will receive invitation to join shared folder—must accept invitation • 10 points: introduce yourself to your instructor • 30 points: complete simple C program • Today’s lecture • Basic C program structure • Comments • Visual Studio demo ECE Application Programming: Lecture 2

3. Our first C program #include <stdio.h>int main(){ printf("Hello World!\n"); return 0;} ECE Application Programming: Lecture 2

4. 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;} ECE Application Programming: Lecture 2

5. 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;} ECE Application Programming: Lecture 2

6. 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;} ECE Application Programming: Lecture 2

7. 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). ECE Application Programming: Lecture 2

8. 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;} ECE Application Programming: Lecture 2

9. 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;} ECE Application Programming: Lecture 2

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

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

12. Variations #3 of first program #include <stdio.h>int main(){ printf("Hello\nthere\nWorld!\n"); return 0;} ECE Application Programming: Lecture 2

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. ECE Application Programming: Lecture 2

14. 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 ECE Application Programming: Lecture 2

15. 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 ECE Application Programming: Lecture 2

16. Comment example /* 16.216 ECE Application Programming Instructor: M. Geiger 1/6/2020 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; } ECE Application Programming: Lecture 2

17. 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! ECE Application Programming: Lecture 2

18. Visual Studio demo • Basics of setting up project • Steps covered in detail in Program 1 spec. • Xcode users: steps are very similar (also covered in Program 1 spec) • 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 ECE Application Programming: Lecture 2

19. Final notes • Next time • Data types • Variables • Reminders: • Sign up for the course discussion group • Respond to poll re: TA office hours • Program 1 due Wednesday, 1/25 • 10 points: e-mail Dr. Geiger for shared Dropbox folder • Please specify e-mail address associated with Dropbox account • You will receive invitation to join shared folder—must accept invitation • 10 points: introduce yourself to your instructor • 30 points: complete simple C program ECE Application Programming: Lecture 2