Lesson 3 McManus COP1006 1

 You have to tell them ◦ what to do ◦ what to use ◦ in what order to do itand ◦ what to do if your user does not do what you want them to do! McManusCOP10062

 Don’t reinvent the wheel!  Use solutions that have been ◦ already proven successful ◦ been created just to be reused McManusCOP10063

 Speed  Readability  Understandability  Maintainability  Reusability McManusCOP10064 We take these into consideration every time we create a program.

 Files ◦ Program – set of instructions ◦ Data – raw pieces of facts McManusCOP10065 database records Data (fields) files

McManusCOP10066

 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 McManusCOP10067

 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” McManusCOP10068

 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 McManusCOP10069

McManusCOP Problem Definition Software & Architectural Design System Requirements Detailed Design Specifications Design Validation Coding* Testing/ Acceptance Operations/ 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. McManusCOP100611

Given DataRequired Results Hours PayRate Gross Pay Processing RequiredSolution Alternatives GrossPay = Hours * PayRate Define the Hours Worked and Pay Rate as constants Define the Hours Worked and Pay Rate as variables Defined the Hours Worked and Pay Rate as input values McManusCOP100612

McManusCOP Calculate Gross Pay Obtain Input Values Calculate Gross Pay Print Pay Check PR HRS PR HRS GP

InputProcessingOutput Hours Worked Pay Rate 1. Enter Hours Worked 2. Enter Pay Rate 3. Calculate Pay 4. Print Pay Gross Pay (the pay check) McManusCOP100614

 Originally used to describe the entire program.  Now, used to define ◦ selection (decision) and ◦ repetition (looping) structures McManusCOP100615

 Flowlines ◦ used when direction is in doubt  Start/(End/Stop/Exit)  Processing  I(input)/O(output)  Decision McManusCOP Begin End Calculate Gross Pay Print Pay Check More Employees?

McManusCOP Snooze or 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. McManusCOP Obtain PayRate Obtain HoursWorked GrossPay equals PayRate Multiplied by HoursWorked Print GrossPay

 Internal  External  Written in different language styles McManusCOP100619

 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 McManusCOP ' 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… McManusCOP 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 McManusCOP100622

 After determining that the solution is correct  Select the appropriate language  Code the program McManusCOP100623

 Test the coded solution  Best done by someone other than the programmer McManusCOP100624

 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. McManusCOP100625

 Nowhere! It is not the purpose to place blame when a fault is found… Only to fix the fault! McManusCOP100626

 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. McManusCOP100627

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