Lecture 1 — Introduction¶

People¶

Demonstrate proficiency in the purpose and behavior of basic programming constructs.
Design algorithms and programs to solve small-scale computational programs.
Write, test and debug small-scale programs
Demonstrate an understanding of the wide spread application of computational thinking to real-world problems.

Practical Programming: An Introduction to Computer Science Using Python by Campbell, Gries, Montojo and Wilson
- Available in e-book form
Very important to get the second edition.
- If you bought the first edition from the campus bookstore you can return it and get the second edition.

Course notes will be posted at

http://www.cs.rpi.edu/academics/courses/fall16/cs1
Piazza will be used for posting homework assignments and labs, and for a public discussion site:

http://piazza.com/rpi/fall2016/csci1100/home

You need to sign up with your rpi.edu account.

Prof. Stewart’s and Dr. Turner’s office hours; others will be posted on-line
Lab sections are held Tuesdays and Wednesdays
Requirements and grading: lecture exercises, labs, homeworks, tests; letter grades
Appealing grades
Class attendance and participation; lecture notes
Homework late policy:
- 3 LATE DAYS FOR THE WHOLE SEMESTER
- 2 LATE DAYS ON ANY ONE ASSIGNMENT
Academic integrity
Other exceptions: report to me right now or as soon as you know
Notes on schedule:
- Labs start this week!
- No labs during the weeks of October 11-15 (Columbus Day, mid-semester break) and November 21-25 (Thanksgiving).
- Test dates are September 26, October 24, and November 21 all at 6 pm.
  - Note that November 21 is the Monday of Thanksgiving week!
- Final exam will be held during finals week. No exceptions! So, don’t make departure plans until the final exam schedule is posted.

We create a text file called hello.py containing just the two lines of Python code:
```
print('Hello, World!')
print('This is Python')
```
This is done by launching the Wing IDE, which is specific to creating and running Python programs
- IDE stands for ’Integrated Development Environment’
- Two windows will appear — the top being the editor and the bottom being the Python interpreter
Load the hello.py program
Run it using the interpreter
We can also type Python code directly into the interpreter.

We are going to emphasize computational thinking throughout the semester, so let’s look at a fun little problem and get started.
This problem is posed in Think Python and taken from the NPR show Car Talk. If you know the answer, do NOT say it!

Find the one word in the English language that contains three consecutive double letters.
We will talk through the steps needed to develop and test a Python program to solve this problem.
- The file containing this program will be posted on the course website after class.
We do not intend that you will understand the details of the program at this time. Rather, this is just an exercise that illustrates the steps of solving a fun problem computationally.
On the other hand, it does introduce some elements that will be seeing repeatedly throughout the semester:
- Files
- Functions
- Loops
- Logic
- Counting
- Output
- Libraries
In about six weeks, you will understand all parts of this program!
You can see the code in three_doubles

Developing an understanding of what the problem is really asking. This usually involves playing around with small examples.
Developing and describing a recipe (an “algorithm”) for solving the problem
- Most recipes will involve multiple parts — multiple functional steps
Turning this recipe into a program in the formal language of Python, one of many different programming languages.
- English is too imprecise for specification of programs.
Running this program using the Python interpreter.

Python is an interpreted language — run immediately and interactively by the Python interpreter, which is itself another (very complex) program
Programs in some other (non-interpreted) languages like C, C++ and Java must be compiled (by a “compiler” — another program) into a new program in machine assembly language and then executed.
In both cases, we write programs that require other programs to run.
- And, we don’t just need just the compiler or interpreter — we need the file system, the operating system, and the command-line interpreter, each of them complicated, multi-part programs themselves.
We don’t really think about the details of these programs; we just think of what they do for us.
- This is called an “abstraction”.
- It allows us to think about a problem we are trying to solve without thinking about all the details of all the other systems we are depending on.
- Thinking in terms of abstractions is fundamental to computer science.

Python has a very simple syntax
- The roles of indentation and blank lines cause the most confusion.
Intepreted languages provide immediate, useful feedback
Python has a powerful set of tools — abstractions
Python is widely used in science, engineering and industry.
Python is good for rapid prototyping
- Sometimes, after a Python program is written and working, the most time-consuming steps are rewritten in either C or C++ and then integrated with the Python code.

A syntax error is a mistake in the form of the Python code that will not allow it to run.
A semantic error is a mistake in the “meaning” of the program, causing it to produce incorrect output, even if it runs.
We will demonstrate both types of errors by deliberately introducing errors in our triple double example program.

By the end of Lab 0, each student will

Sign up at the course Piazza web site

https://piazza.com/rpi/fall2016/csci1100/home
Go to the course page

http://www.cs.rpi.edu/academics/courses/fall16/cs1/python_environment.html

and follow the instructions to install the Python environment on her/his computer.
- There are installers for “native” versions of the environment for Windows, Mac OS X and Linux machines.
Create a Dropbox account to store back-up copies “in the cloud” of homework and lab solutions and lab for the course.
- Other cloud-based back-up copies are acceptable.

Students are encouraged to get started before lab, including downloading the environment.