1. CST 1101 Problem Solving Using Computers

2. CST 1101
Topic 02: “Hello World”

3. What Makes Learning Python Important?
Python lets you work quickly to integrate systems as a scripting or glue language. It’s also suited for Rapid Application Develop (RAD).
The game Civilization 4 has all its inner logic, including AI, implemented in Python.
NASA uses Python in its Integrated Planning System as a standard scripting language.
Features:
Simple to learn and easily read
Associated web frameworks for developing web-based applications
Free interpreter and standard library available in source or binary on major platforms

4. Who Uses Python? Professions and Industries:
Python developers, software engineers, back end developers, Python programmers
Used by employers in information technology, engineering, professional services and design
Major Organizations: Google, Pinterest, Instagram, YouTube, DropBox, NASA, ESRI
Specializations and Industries: Web and Internet development (frameworks, micro-frameworks and advanced content management systems); scientific and numeric computing; desktop graphical user interfaces (GUIs)

5. Why Python? Python is a scripting language :
Free
Portable
dynamically-typed
object-oriented
Python Combines software engineering features of traditional systems languages with power and flexibility of scripting languages.

6. Traditional vs Scripting Languages
Traditional languages (C++, Java) evolved for large-scale programming
Emphasis on structure and discipline
Simple problems != simple programs
Scripting languages (Perl, Python, TCL) designed for simplicity and flexibility.
Simple problems = simple, elegant solutions
More amenable to experimentation and incremental development
Python: Ideal first language, useful throughout curriculum (Information and Data Management, Data Mining)

7. Running Python Programs
Hybrid compiled/interpreted architecture
We will use Integrated Development Learning Environment (IDLE), an integrated development environment for Python and Python 3.6
Options:
Start Interpreter from command line (>>> )
Type program statements
Import script file
Directly from IDLE

8. Download IDLE and Python

9. IDLE A quick way to launch IDLE is from Window’s Start Menu
 choose IDLE (Python GUI)
If you use Windows 10, see the example
For Windows 7 or Vista see the example in the HowToStartIDLE.pdf tutorial

10. IDLE Shell
Put the statement that you want to be displayed on the screen in double quotes. This is a String type that we will discuss later.

11. >>>help() command starts interactive help
Ctrl-C command exits interactive help
Interactive help for the if operator

12. Creating and Running a Python program
To create a new Python program, choose File  New File to open a text editor window
A new window will be open
for editing
To save do File  Save as
To run do Run  Run module or click F5

13. Saving file
If the file that you try to run does not have all the recent updates you will see the following window. Click OK, follow the prompt and save your work

14. Comments Comments improve code readability and documentation
Comments are not executed by a computer (a compiler skips them):
Comments are for programmers and users
Comments are not for computers

15. Comments Start comments with # – the rest of line is ignored.
Can include a “documentation string” as the first line of any new function or class that you define.
The development environment, debugger, and other tools use it: it’s good style to document your code with comments.

16. Using Python Shell as a Calculator