CS 110

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CS 110

• Introduction to Computer Programming

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CS 110 Instructor
Name Dr. Jack Tumblin Office Computer Science
Dept., 1890 Maple Ave. Rm. 350 E-mail
j-tumblin_at_cs.northwestern.edu Office Hours Mon,
Fri 100-300pm, or by appt. Phone
(847)-467-2129 (use sparingly)
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Class Meeting Places
Monday, Wednesday, Friday at 1000AM Tech,
MG-28 (this room) Tuesday at 1000AM Tech
MG-51 (the computer classroom) for hand-on
programming practice help
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Resources

• class newsgroup cs.a10 GONE!!! ?Use Course
  Management System
• Use to
• discuss class material,
• ask questions on the material or the assignments
  (but NEVER post solutions)
• share solutions to posted practice problems

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Resources

• class webpage http//www.cs.northwestern.edu/aca
  demics/courses/a10
• ?CHANGING to Course Management System
• Use to
• download class notes and assignments
• access helpful tutorials
• look up information about the class (e.g.
  policies)
• look up your grades

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Resources

• Teaching Assistants
• Drop-by Lab Hours 4 TAs x 3 Hours/week ?
  Plenty of help!
• Newsgroup Questions Answers
• Weekly In-Class Lab
• Hands-on help
• Practice problems and exercises
• See good problem-solving as it happens

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What is a Calculator?

• What is a Computer?
• Whats the difference?
• A vague notion in our textbook
• history makes it plain and clear

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What is a Calculator?

• Before 1940s Manhattan Project A meticulous
  person employed to make large series of numerical
  calculations. for fluid flow, ballistics, trig.
  tables, bombs, etc
• Sometimes helped by usingmechanical
  calculating machines
• Seehttp//www.lanl.gov/worldview/welcome/history
  /22_computers.html

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What does a Calculator do?

• Before 1940s Manhattan Project (Women were
  consistently the best calculators by far)
• Teams of calculators would
• Read card(s) with list(s) of numbers
• Follow step-by-step instructions to compute new
  numbers
• Write new numbers, arrange new cards
• Tabulate, print, graph, or results.

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What is a Calculator?

• Before 1940s Manhattan Project (Women were
  consistently the best calculators by far)
• Teams of calculators would
• Read card(s) with list(s) of numbers
• Follow step-by-step instructions to compute new
  numbers
• Write new numbers, arrange new cards
• Tabulate, print, graph, or results.

Input Data
Process Data
Output Data
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What is a Calculator?

• Answer a reliable follower of fixed rules
  for modifying numbers (data).
• Read Write
• Numbers Numbers

Process Data
Input Data
Output Data
Follow Instructions to make new numbers
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What is Data?

• Data numbers with assigned meanings
• Numbers can mean anything!
• Alphabet letters 41A, 42B, 43C,
• Colors 0Black, 128Gray, 255White
• Decisions 0No, 10Maybe, 20Yes,Data can
  follow ANY rules you define!

Process Data
Input Data
Output Data
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What is a Computer?

• Now suppose that we have a calculator, PLUS
• A vast, huge list of numbers we can change
• Calculator instructions to read and write numbers
  at any desired place on the list
• An ID for every calculator instruction 00
  add, 01 subtract, 02 is less than, 03read
• A way to run the calculator from IDs read from
  the list
• THEN the rule-follower can change its own
  rules!
• THIS is a computer! a unified, stored program,
  stored data device...

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What is a Computer ?

• Read Write
• Numbers Numbers

Process Data
Input Data
Output Data
Instruction Follower
Instructions(numbers) ------------------- Data
(numbers)
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Now what is a Computer?

• A rule-following engine that
• Converts input data
• to output data
• by following instructions that it can
  change, just like data!
• A calculator that pushes its own buttons
• Storage for lists of numbers (memory).
• numbered instructions (press 2 for add)
• ability to follow instructions stored as numbers

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Why Bother with Computers?

• A computer is
• A fast, tireless, rule-following machine
• An engine to mimic ANY rule-based system
• You write the rules the computer solves the
  problem
• Abstractions exist for almost ANY
  problem(including how can I write a good
  program)

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What You Will Learn

• How to solve any finite, defined problem by
• writing orderly sets of rules (functions) that
  are
• applied to orderly sets of data (structures), and
• Re-using earlier solutions (libraries)much less
  tedium.
• Core ideas found in ALL programming languages
• The Visual Studio programming environmentone
  good tool among the many available.

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What is Programming?

• Program A sequence of human-readable
  instructions telling a computer how to do a
  particular task or solve a given problem.
• Programming Designing, writing, and testing a
  computer program that works.

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Programming Artful Common Sense

• 1) Analyze Find the Core Problem
• (not how to solve it).
• Decide the specific inputs and outputs, and
• Define how to make outputs from inputs
• Break it down into sub-problems,
• 2) Implement Write a rule set (a function) for
  each,
• 3) Debug Bottom up Test each function
  separately then link them together, test, until
  it all works.

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1. Analyze Find the Core Problem

• House Example
• Write a program that computes the square footage
  of a house, given the dimensions of each room.
• Input
• The number of rooms (an integer)
• The dimensions of each room (real numbers)
• Output
• The square footage of the house (real numbers)

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1. Analyze Find the Core Problem

• Be sure you really understand problem!
• Refine, simplify, clarify, think. Repeat.
• Decompose it into sub-problems
• First ideas are NEVER the best ones.
• House Example
• subproblem 1 compute the area of a room
• subproblem 2 add up area of all rooms

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2. Implement

• Translate your sets of rules into C language
  syntax (try not to garble it too much).
• We will learn how by exploring
• Variables, Types, Statements, Expressions,
  Assignments, Conditionals and control flow
  constructs, functions, and more.

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2. ImplementCompiler Linker

• C is a compiled language it is meant to be
  human-readable.
• Compiler a converter program
• human-readable ? machine-executable
• Compile C text file(s) ? object file(s)
• Linking object file(s) ? .executable file

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3. Debug

• Two Kinds of Programming Mistakes
• Syntax Misteaks (easy to fix compiler helps)
• Design Mistakes (harder you must THINK)
• Computer Jargon
• bugmistake
• To debug to find and fix your mistakes

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3.Debug Find Fix Mistakes

• Write C ? Compile ? Run, repeat
• Does it compile?
• NO? compiler says why. Modify C, try again
• YES. Does it work right?
• NO? analyze, modify, try again.
• YES. But does it ALWAYS work right?
• (can you prove your analysis is robust?)

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Conclusions

• Lets Get Started! As soon as you can,
• Read Chapter 1 of textbook
• Find computer labs, log in, and
• Visit website, look around
• Visit newsgroup try test message
• Start Up Visual C, read welcome info
• Try Assignment 0 (on website)
• Come to Lab Session on Friday in MG51

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END

• END

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What is input and output?

• Input/Output conversions between numbers
  ??meaningful things
• Arm finger moves (mouse, joystick, keyboard)
• Text, spelling, grammar, analogy, reasoning
• Molecules, synapses, neural signalling, brains
• Music, speech, noise, vibration, resonance
• Image, picture, vision, sketch, light, shadow
• Robotics, actuator movement, collision, routes
• Fluid flow, compression, shock waves,
• AND
• Computer programming ideas??instructions

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Dont PanicC Programming 8 Key Ideas

• All brilliant ideas are simple FmA, be nice to
  people,etc.
• Computer Science is new few great ideas (yet)
• Example Programming 3 kinds of instructions
• Do this list of steps
• If (A is true) , do that list of steps
• Do this list of steps again.
• All the rest (entire book contents) are minor
  details, elaborations, and shortcuts to make
  things easier!