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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
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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 1st course. Not as theoretical as 2nd 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