1. CS31 Discussion 1H Fall18: week 1
TA: Behnam Shahbazi
Credit to former TAs: Chelsea Ju and Bo-Jhang Ho

2. Today’s Topic Project #1 IDE Setup and Configuration
Brief C++ Introduction
Run Programs on Local & Seasnet
We’ll do it together
Compilation Errors vs Runtime Errors vs Wrong Answer

3. How am I? My name is Behnam
“Beh” means “best” in Persian and “nam” means “name”.
6th Year PhD student – Computer Science Dept.
Research area: Text mining, NLP, Machine Learning
Fan of playing sports like Soccer and Ping Pong

4. Resources My Office Hour & Location My Email
Wednesday 8:30am – 11:30am
Boelter 3256S My
Instructor’s & other TAs’ office hours

5. Grading Homework: 40% Midterm: 25% Final exam: 35% Assignments: 40%
7 projects
The work should be submitted electronically
Late submissions will be penalized by every second
Midterm: 25%
 Thursday, October 25
Thursday, November 15
Final exam: 35%
Saturday, December 8
Assignments: 40%

6. Don’t give up!! Learning Tips Keep up with the lecture material
Start early
Problem solving & coding may take longer than you think
Read carefully
Double/Triple check the project requirements
Develop incrementally
Add bits of code at a time, then compile, and run.
It is easier to isolate any bugs, and to understand if the code is doing what you expected
Don’t give up!!

7. Project #1 Due 11pm Monday October 8, 2018
Read the specification carefully, don’t get a 0 in any assignment!
What to submit?
C++ scripts
original.cpp
logic_error.cpp
compile_error.cpp
Report in MS Word format or Plain text
report.doc or report.docx or report.txt
Discuss any error messages the compiler reports, and incorrect/unusual results.
Compress everything into one zip file, and submit online.

8. IDE Configuration IDE = Integrated Development Environment
A programming environment that has been packaged as an application program
A graphical user interface (GUI), and a code editor
A compiler
A debugger
A lot of different tools (energy analysis, CPU utilization, …)
More on Class website
Mac
Linux
Windows
Xcode
Command Line
Terminal
- Visual C++

9. Demo – Let’s rock! Demo Xcode Old-fashion way to write code
VIM to write code
Use terminal to compile code and execute binary
Useful commands to know: cd, ls, pwd, mkdir, “cd ..”, …
Let’s run our code on Seasnet
Connect to seasnet (example):
Example:
ssh
ssh
Copy your code on seasnet:
scp PATH_TO_FILE/file.cpp

10. Example #1 – A simple program
Make groups of two people
Please just copy and paste this to your code editor and run it
#include <iostream> using namespace std; int main() { cout << "Hey, this really works!" << endl; return 0; }

11. Example #2 – A simple interactive program
Please just copy and paste this to your code editor
#include <iostream> using namespace std; int main() { int num; cout << "Hey, give me a number: "; cin >> num; int numSquare = num * num; cout << "The square of this number is " << numSquare << endl; return 0; }

12. Details of build process
What exactly is going on when I click ?
The hint from Xcode (the IDE)

13. Details of build process
What exactly is going on when I click ?
The hint from Xcode (the IDE)
Source code
Executable or
Binary
Run the program

14. Details of build process
What exactly is going on when I click ?
The hint from Xcode (the IDE)
Compile (Build)
Execute a program
Source code
Executable or
Binary
Run the program

15. Demo how to write a program using a terminal (Linux environment)
Demo time

16. Why do we need to compile a program?
Compile the source code by a compiler
Source code (human readable)
Executable/binary (machine readable)

17. What is C++?
Is a (programming) language so that you can create a valid computer program
C++
C++ C
Assembly
Machine code (Binary)

18. What is C++?
Is a (programming) language so that you can create a valid computer program
C++
C++ C
Assembly
Machine code (Binary)

19. What is C++?
Is a (programming) language so that you can create a valid computer program
C++
Object-oriented language
C++
Procedural
language C
Assembly
Machine code (Binary)

20. Let’s make some errors - 3 types of errors
Compilation error
Syntax error
Undeclared identifier
Common function undeclared
Program crashes (Segmentation fault)
The program runs into an invalid state
Incorrect memory access
Runtime error
Logic error
Wrong answer

21. The skeleton C++ code
This is the only time in this quarter I ask you to memorize codes!!
#include <iostream> using namespace std; int main() { return 0; }
Let’s go through some examples

22. Example #3 – Another interactive program
What is cin and cout?
#include <iostream> using namespace std; int main() { int i, j; cout << "Please enter the value for i: " << endl; cin >> i; cout << "Please enter the value for j: " << endl; cin >> j; cout << "i + j = " << i + j << endl; return 0; }

23. Example #3 – Another interactive program (Cont’d)
Potential errors you can get:
Unbalanced bracket
Missing semicolon
Undefined variable
Undefined operator
No number after return keyword
Library doesn’t exist
Etc.

24. Example #4 – Division Any errors we may get?
#include <iostream> using namespace std; int main() { int i, j; cout << "Please enter the value for i: " << endl; cin >> i; cout << "Please enter the value for j: " << endl; cin >> j; cout << "i / j = " << i / j << endl; return 0; }
Any errors we may get?

25. Example #5 – What’s wrong with this code?
#include <iostream> using namespace std; int main() int a = 10; cout << A << endl; return 0; }
Paste it to your programming editor to find the answers

26. Example #6 – Access invalid index in an array (advanced)
#include <iostream> using namespace std; int main() { int arr[100]; arr[ ] = 3; return 0; }
Since there are only 100 available spots whose index ranged from 0 to 99, write back to any other index beyond this range will screw the memory and may crash the program

27. For project 1 – generate some bugs
You may want to explore the language a little bit… If
Array
For loop / while loop