Lesson 3

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You have to tell them ◦ what to do◦ what to use◦ in what order to do it and◦ what to do if your user

does not do what you want them to do!

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Don’t reinvent the wheel! Use solutions that have been

◦ already proven successful ◦ been created just to be reused

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Speed Readability Understandability Maintainability Reusability

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We take these into consideration We take these into consideration every timeevery time we create a program. we create a program.

Files◦ Program – set of instructions◦ Data – raw pieces of facts

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database

records

Data (fields)

files

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DBMS

Database Management Systemmade up of one or more databases

DB

A databasemade up of one or more tables, queries, forms, reports, etc

Tableinformation related to one topicmade up of one or more records Rooms Instructors

Record

information related to one specific entitymade up of one or more fields Inventory Classes

Field

information related to one specific part of an entitymade up of one particular data type

Item NameItem Number

Student NameStudent SSN

Northwest Florida State College

FWB

ExampleDefinition

Memory location Used to store data during transfer between

internal memory and the external storage (hard drive or floppy)

Speeds up transfer of information◦ Input & output processes

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Semantics◦ The concept or idea of the item◦ Ex. The numeral three is an idea that humans

have established representing the concept of three items

Syntax◦ The physical/visible representation of the idea ◦ Ex. “three” “3”

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Tools◦ Problem Analysis Chart (PAC)◦ Structure/Interactivity Charts◦ Input Processing Output (IPO) Chart◦ Flowcharts◦ Hierarchy Charts

But…first we have to understand the Software Life Cycle

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Problem Definition

Software & Architectural DesignSystemRequirements Detailed Design

SpecificationsDesign Validation

Coding*Testing/

AcceptanceOperations/

Maintenance

Indicates= reiterative steps after testing and verification of each phase

*Implementation

The Waterfall Model

Understand the Problem Analyze the Requirements of the Problem Figure out what will be the outcome

Very often we’re not given the inputs to a problem, only the desired output.

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Given Data Required ResultsHours

PayRate

Gross Pay

Processing Required Solution AlternativesGrossPay = Hours * PayRate Define the Hours Worked and Pay

Rate as constantsDefine the Hours Worked and Pay Rate as variablesDefined the Hours Worked and Pay Rate as input values

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Calculate Gross Pay

ObtainInput Values

Calculate Gross Pay

Print Pay Check

PR

HRS PR

HRSGP

GP

Input Processing Output

Hours Worked

Pay Rate

1. Enter Hours Worked

2. Enter Pay Rate

3. Calculate Pay

4. Print Pay

Gross Pay (the pay check)

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Originally used to describe the entire program.

Now, used to define ◦ selection (decision) and ◦ repetition (looping) structures

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Flowlines◦ used when direction is in doubt

Start/(End/Stop/Exit) Processing I(input)/O(output) Decision

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Begin End

Calculate Gross Pay

Print Pay Check

MoreEmployees?

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Snoozeor Off?

Alarm goes off!

Sleep or Get up?

Zzzzz!

Snooze

Sleep

Get Dressed. . .

Snooze= 9?

< 9

Ignore Alarm, Forget Boss,

Forget Instructor – Probably creating a problem?

Everything is included, but written in English rather than any one language’s syntax

Useful for debugging Ex.

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Obtain PayRateObtain HoursWorkedGrossPay equals PayRate Multiplied by HoursWorkedPrint GrossPay

Internal External

Written in different language styles

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Used to explain what is being done (and why) within the program

Most often takes the form of comments within the program◦ Written in Language that Programmer, not user,

will understand

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' Insert a new node in the binary search tree.

' If the root node is null, create the root node here.

' Otherwise, call the insert procedure of class TreeNo

Manuals or Help menus to assist the user◦ Includes

User Manuals System Manuals

User must be able to understand…

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Make text bold

1. Select the text you want to change.

2. Click Bold on the Formatting Toolbar.

Walkthroughs◦ Walking through the process to verify that the

solution is solving the right problem and works correctly

◦ You can use any of the charts or Pseudocode for this step

Helps find bugs

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After determining that the solution is correct

Select the appropriate language Code the program

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Test the coded solution Best done by someone other than the

programmer

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found in large-scale software projects are specification and design faults.

Where do most of these faults originate?◦ Not fully understanding the problem and ◦ then creating a specification based on an

erroneous problem definition. Industry’s high priority

◦ involves the development and use of techniques that will help find faults during the earliest phases.

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Nowhere!It is not the

purpose to place blame when a fault is found…

Only to fix the fault!

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new problems arise, such as:◦ different styles of writing code, ◦ interface difficulties, ◦ different declared types (integer vs real)◦ different understandings of the problem caused

by communication problems, and ◦ even something as simple as the order in which

variables are listed within a procedure’s call statement.

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