C and

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C and Object-Oriented Programming Overview
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Analysis and Design

• Goals for this Lesson
• Understand an example of program development
• Understand the characteristics of a good
  algorithm
• Understand how algorithmic patterns can help you
  design programs
• Provide the deliverables for two phases of
  program development Analysis Design
• Complete exercises for Analysis Design Projects

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Program Development

• One program development strategy has these three
  steps
• Analysis Understand the problem
• Design Organize the solution
• Implementation Get the solution running
• Program development is the progression from
  analysis to design to implementation
• There are deliverables from each phase

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Deliverables

• Analysis deliverable
• A document that lists the data objects
• Design deliverable
• An algorithm that outlines a solution
• Implementation deliverable
• An executable program that provides the solution,
  error free

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Analysis

• Synonyms
• inquiry, examination, study
• Activities
• Read and understand the problem statement
• Name the pieces of information (data) necessary
  to solve the problem
• these data names are part of the solution
• data names (identifiers) should be standard

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Self-Help Exercise

• Example
• Compute maximum airplane takeoff weight.
• Name a data object that stores the answer
• _________________________
• Name the data object(s) that must be supplied to
  compute that answer
• _________________________

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There is more to datathan the names ...

• The data things are called objects and have these
  three important characteristics
• a name
• state a.k.a value(s)
• a set of operations to manipulate the state
• Encapsulation
• conceals the functional details of a class

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Input and Output

• It will help in the early programming projects to
  distinguish objects that are either input or
  output
• Output Information the computer must display
  after the processing has occurred
• Input Information the user must supply to solve
  the problem.

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Sample problems help

• It also helps to provide sample problems
• given specific input data, determine the output
  (result shown on the screen)
• Find the length of a line
• x1 1.0
• y1 1.0 Input
• x2 5.0
• y2 4.0
• length 5.0 Output

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3
4
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Other Sample Problems
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Summary of Analysis

• Activities performed during analysis
• Read and understand the problem
• Decide what object(s) represent the answerthe
  output
• Decide what object(s) the user must enter to get
  the answerthe input
• Create a document that summarizes the analysis.
  This document is input for the next phase of
  program developmentdesign

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An Example of Analysis

• Produce the analysis deliverable for the
  following problem
• Problem Using this course grade scale,
• Grading Element Percent of Grade
• Test 1 (0.0 to 100.0) 25
• Test 2 (0.0 to 100.0) 25
• Final Exam (0.0 to 100.0) 50
• compute a course grade as a weighted average for
  any combination of two tests and one final exam.

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Self-Help Exercise

• Complete this analysis document and two sample
  problems see slide 1-9 for three examples
• Problem Object Input or Sample Sample
• Statement Names Output Problem 1 Problem 2
• Compute
• course
• grade
• using
• grading
• elements

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Design

• Synonyms of design (verb)
• model, think, plan, devise, pattern, propose,
  outline
• We'll use these design tools
• algorithms
• algorithmic patterns
• algorithm walkthroughs

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Algorithms

• An algorithm is a set of activities (usually
  step-by-step) that solves a problem.
• An algorithm must
• list activities that are to be performed
• list these activities in the proper order

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Bake a Cake

• A recipe (a.k.a. an algorithm)
• Preheat Oven
• Grease Pan
• Mix ingredients
• Place ingredients into pan
• Place pan in oven
• Remove pan after 35 minutes
• Switch some activities around
• What's missing?

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Algorithmic Patterns

• Pattern Anything shaped or designed to serve as
  a model or guide in making something else.
• Algorithmic Pattern A pattern that occurs
  frequently during program development.
• The Input/Process/Output (IPO) Pattern is used
  during this lesson.

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IPO Algorithmic Pattern

• Pattern Input/Process/Output (IPO)
• Problem The program requires input to
  generate the desired Info.
• Outline 1. obtain input data from user
• 2. process input data
• 3. output the results

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Patterns ala Alexander

• "Each pattern describes a problem which occurs
  over and over again in our environment, and then
  describes the core of the solution to that
  problem, in such a way that you can use this
  solution a million times over, without ever doing
  it the same way twice."
• From A Pattern Language, Christopher Alexander,
  Oxford University Press

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Example of Algorithm Design

• The deliverable from this design phase will be an
  algorithm.
• The IPO patterns provides a guide to design this
  more specific algorithm (that is a bit sketchy)
• IPO Model One Specific IPO Case Study
• Input Obtain test1, test2, and finalExam
• Process Compute the course grade
• Output Display the course grade

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Refining steps in algorithms

• We often need to refine some steps.
• For example, Compute the course grade might now
  be refined with the C mathematical addition
  and multiplication operators and the names for
  the objects
• courseGrade test1 0.25
• test2 0.25
• finalExam 0.50

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Algorithm Walkthrough

• Suggestion Use an algorithm walkthrough to
  review the algorithm
• Simulate what the computer would do if given the
  instructions.
• if input occurs, copy values by object names
• if processing occurs, change an object's value
• if output occurs, write that output

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An example walkthrough

• I) Retrieve some example values from the user and
  store them into the objects as shown
• test1 ? 80 test2 ? 90 finalExam ? 100
• P) Use input data and compute courseGrade as
  follows
• courseGrade (0.25test1)(0.25test2)(0.50final
  Exam)
• (0.2580.0) (0.2590.0)
  (0.50100.0)
• (20.0 22.5 50.0)
• courseGrade 92.5
• O) Show the course grade value to the user
• Note Retrieve the data stored in courseGrade to
  show
• 92.5

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Implementation

• Synonyms for Implementation
• accomplishment, making good, execution
• Implementation deliverable computer program

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The Virtual Machine Concept

• Let's accept the fact that we're not going to
• translate our algorithms into machine code
• implement the operating system needed to execute
  programs
• and so on
• Instead, let's view the computer as a virtual
  machine
• an abstract view of the computer

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Seven Levels of Abstraction

• Level Virtual Machine (abstraction)
• 6 Application Software
• 5 Programming language
• 4 Assembly language
• 3 Operating system
• 2 Machine language
• 1 Microprogram
• 0 Digital logic

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The various levels of abstraction

• User view the computer from level 6
• Programmers view the computer from level 5 (this
  is where we are at now)
• We translate a level into a lower level using the
  tools of that lower level.
• The tool we'll used is known as C

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Example Translations

• Psueduocode algorithm
• Display the value of courseGrade
• Our programming language translation
• cout ltlt "Course grade " ltlt courseGrade
• Once the algorithm is translated into a
  programming language abstraction
• use the compiler to generate machine code
• use the linker to create executable program
• run the program
• test the program

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C Source Code

• include ltiostream.hgt // for stdcout, stdcin,
  and stdendl
• int main()
• // Declare and initialize the numeric objects
  (variables)
• double test1 0.0
• double test2 0.0
• double finalExam 0.0
• double courseGrade 0.0
• // I) Obtain input
• cout ltlt "Test 1 "
• cin gtgt test1
• cout ltlt "Test 2 "
• cin gtgt test2
• cout ltlt "Final Exam "
• cin gtgt finalExam
• // P) Process courseGrade
• courseGrade (0.25test1) (0.25test2)
  (0.50finalExam)
• // O) Display the value of courseGrade
• cout ltlt "Course grade " ltlt courseGrade ltlt endl
  
• return 0

Optional Demo grade.cpp
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Testing

• Testing occurs at any point in program
  development
• Analysis example problems
• Design algorithm walkthroughs
• Implementation run program with several sets
  of input data
• A running program isn't always right.
• but we can gain confidence that it is

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Overview of the program development process by
levels of abstraction
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Objects and Classes

• Objects are entities stored in memory.
• We understand an objects through its
• the value(s) it stores
• the operations that can be applied
• The case study used four numeric objects (double)
• values each object of the double class stores
  one floating point number
• operations operations such as input (cingtgt),
  output cout ltlt, assignment courseGrade ,
  addition , and multiplication

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Objects

• Every object has
• A name
• State--value(s) stored in memory
• Operations
• examples , , -, cin gtgt, cout ltlt, sqrt,
  length, width push_back, pop, capacity, resize

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Characteristics of Objects

• Name
• All four double objects have their own unique
  name.
• State
• The state of the double class objects was set
  either through an input operation like this
• cin gtgt test1
• or through an assignment operation
• courseGrade 0.25 test1 0.25 test2
• 0.50 finalExam

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Operations applied to objects

• Operations
• Addition and multiplication operations are
  applied to some double objects
• 0.25 test1 0.25 test2 0.50 finalExam
• There is an input operation applied to the
  keyboard object named cin
• cin gtgt test1 // This alters test1
• The state of courseGrade is examined through an
  output operation (cout is the name of the
  screen)
• cout ltlt courseGrade

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Classes

• A class defines the value(s) stored by an object
  and the operations that may be applied to objects
  of that class.
• A program may utilize many instances of the same
  class.
• Each instance of class is also know as an object

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One class--many objects
aNumber
maximum_Takeoff_Weight
x
double
finalExam
test1
y
test2
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Some Standard C Classes
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Self-Help Exercise

• Which class of object and what name would you use
  to represent each of the following?
• The number of students in a course _____ _____
• An effective annual percentage rate _____ ______
• A persons name _______ ________
• Obtain keyboard input ______ _________
• An employee (trick quest.) ________ ________
• All employees in a company _______ _________