Class 1: What this course is about
Assignments
• Reading: Chapter 1, pp 1-33
• Do in Class 1:
– Exercises on pages 13, 14, 22, 28
• To hand in in Class 2:
– Exercises on p 33
In a nutshell
• This course is about writing computer
programs which solve problems
– First step: ‘grok’ the problem. (Look up the
meaning and origin of ‘grok’.)
– Second step: write the program
– Third step: make sure the program correctly
solves the problem
What is an algorithm?
• An algorithm is an unambiguous, step-bystep procedure for solving a problem
• A recipe is an example of an algorithm
• An algorithm provides the design for a
computer program
What is a computer language?
• A computer language is a notation for
writing down algorithms
• ‘High level’ languages are readable, like
natural human languages
• Computer languages are precise enough to
be executed by (unthinking) machines
• All computer languages are fundamentally
equivalent in their expressive power
What is a program?
• A program is a set of instructions written in
a computer language
• A program implements an algorithm
• A program written in a high-level language
may be translated into a low level language
(the natural language of a computer)
What is a computer?
• A computer is a machine that executes
programs (unlike a lawn mower)
• A computer can execute any program
(unlike a CD-player)
• Since computers are Universal Machines,
they are all fundamentally equivalent in
computing power
How do you write a program?
• A computer can execute programs that are tools
for creating programs
• The programmer’s everyday tools are:
– editor
– interpreter or compiler
– debugger
• A suite of such tools is called an integrated
development environment (IDE)
• We are using the Idle IDE for Python
The editor
• An editor is used to write programs
• Programs are written in plain text
• The file containing the program in a highlevel language is called the source file
• A Python source file has the extension ‘.py’
The interpreter
• An interpreter translates from a high-level
language to the computer’s language
(instruction set)
• The Python shell interprets line by line.
• A line of computer code can not be
translated and executes unless it is
syntactically (grammatically) correct
Debugging
• Just because you’ve written some code
doesn’t mean you’ve solved your problem.
• Testing is the process of trying to discover
errors in your program.
• Debugging is the process of fixing errors
you discover.
• (The sentence ‘Colorless green ideas sleep
furiously’ is grammatically correct, but
what does it mean? Look in up on the Web.)
Panic abatement advice
• Expect to spend lots of time
– Programmer wisdom: it always takes longer
than you think
• Expect things to go wrong
– Murphy’s law of computers: anything that can’t
go wrong, will
– Don’t panic: every bug has a fix
Tips for success
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Start every assignment early
Don’t fall behind
Ask if you don’t know
Do your own work
Getting help
• Use the online help system
• Every CA and instructor has office hours
• Sign up for one of the study/homework
sessions (hint: best right after class)
• Learn to work with a partner or team as well
as to tackle problems on your own.
Grading
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Homework (almost every class) 15%
Roadmap projects
15%
Midterm 1
20%
Midterm 2
20%
Final
25%
Misc
5%
All sections have same work and tests
Course is graded on a curve
Attendance
• Lecture attendance is mandatory (you are
asked to sign in). Five absences will lead to
withdrawal
Homework
• HWs are handed in paper (hard copy) and
electronically
• No late HWs will be accepted
• Every HW hard copy must be neatly printed
and stapled
• Every HW must have student name and ID,
date, HW # and section #
Honesty
• Cheating on an exam will result in failing
the course
• You may discuss HW problems with each
other
• You may not take credit for something you
did not do