Python – May 11 Briefing Course overview Introduction to the language Lab

Python Why computer programming? –Computer is a general-purpose machine, born to be programmed –We want to solve many types of problems Our goals –Become multi-lingual –Practice with design & implementation –Learn by doing: start simple Help available –Textbook, python.org, tutorials

Background First released, 1991 –Guido van Rossum, CWI, Netherlands –Dissatisfaction with existing languages High-level, multi-purpose language –Relatively easy to learn & use (we hope!) –Procedural, object oriented or functional –Interpreted –Interface to OS, file system, Web –Some data structures built into language –Standard library –(More details in sections 1.3 and 1.5)

Initial To-Do Essential skills; special features of language Routine stuff –Source file name ends in.py –How to run interpreter (command line or IDE) –Program structure I/O –Interactive, file; formatting Variables, identifiers Doing math Comments, tokens, whitespace, style conventions

continued Control structures –Asking questions, repeating stuff –nesting –How to make comparisons –Boolean operations: and/or/not Functions/procedures: parameters, returns Data structures –String, dynamically-sized list, etc. Standard (i.e. run-time) library –Random numbers, etc.

In the end… How can you tell if you’ve mastered a language? –Write a game –Given a spec or algorithm, can you implement it? –You may prefer to do something in Python! –You never need to know everything. Know where to find stuff quickly This course lies between first 2 prog. courses –You’ll see more operations & applications than in the 1 st course. Not as theoretical as 2 nd course.

Beginning Versions 2.x and 3.x Lab: let’s use IDE such as ActivePython –Free, simple, includes debugger Code can by entered: –directly in shell (good for experimenting!) –in a file, which we can save and reuse later

Initial nuts & bolts Comments begin with #, go to end of line Statements don’t end in semicolon Don’t arbitrarily indent code Put \ at end of line to continue statement Variables are not declared Interactive output –Version 2.6: print statement print name –Version 3.0: print function print (name)

continued Examples print “Hello, world” print 7+4*3 Interactive input –input( ) for getting a number –raw_input( ) for getting a string name = raw_input(“What is your name”)

What’s next? Lab Please read chapter 2 Practice with –Basic I/O –Mathematical operations –Strings –Simple if statement –Simple loop