Software Engineering - Prelims

Capacitor (diagram)

Diode (diagram)

Resistor (diagram)

2-way switch (diagram)

on/off switch (diagram)

Speaker (diagram)

Motor (diagram)

LED (diagram)

Lightbulb (diagram)

Integrated circuit (diagram)

Voltage source (diagram)

DC Voltage Source (diagram)

Amplifier (diagram)

Structured/Waterfall Approach

go through each step one at a time in a linear process

Choosing structured approach is influenced by

size and nature of product skills of people involved detail of requirements finances available

What the structured approach is good for

large scale projects with big teams and budgets

Stages of structured approach

Requirements; Determining specifications; Design; Development; Integration; Testing and Debugging; Installation; Maintenance

Remembering Stages

ReStoreDogDoorIdentityTIM

Agile Approach

manage multiple stages at once allowing sudden changes and the ability to work backwards

What the agile approach is good for

small-to-medium organizations; no deadline; requirements aren’t clear; unsure of market need; constant customer involvement

Requirements

general descriptions of services/feature expected from the system from the customer that need to be understood completely

Analysis of requirements

surveys; interviews; time management studies; Business analysis

Determining Specifications

written based off requirements and answering the ‘how’ in design (what the system will do to achieve that requirement)

Functional requirements/specifications

how users interact with the system (e.g. requirement: customers need to be able to search so specification: search bar)

Non-Functional requirements/specifications

performance and quality of the system (e.g need to be compatible with other softwares)

Design

creation of system models and project planning where we identify data types/structure; variable naming convention; algorithms needed

Project planning

use gantt charts or journals or diaries or logbooks or system modeling tools (storyboards and flowchart)

Development

coding the solution with the use of IDEs

IDEs

Integrated Development Environments (programs that have tools like error detection and debugging; Microsoft’s visual studios)

Integration

see how the code works with other softwares and databases (e.g. paypal)

Version control

software that tracks and manages code while multiple people work on it

Version control example

Git that can merge versions and branch versions and snapshot specific points of time when people edit the code

Testing and Debugging

Involves different stages of testing the code/software and the use of correcting any code that doesn’t work

Types of testing

Alpha and Beta testing

Alpha Testing

software/code is tested by the people who know about the software before hand or knows how it works (this is done first before beta)

Beta testing

program is distributed to selected outsiders who test and report back any problems or bugs and also give feedback

Why is testing and debugging important

Ensures the quality assurance and that it meets all requirements and specifications

Quality assurance

represent our goals of ensuring the product meets all requirements set at the start

Levels of testing

Module testing; program testing; system testing

Module testing

test each individual subroutine/module withing a program AS its being created

Program testing

each program tested to ensure modules work together correctly

System testing

testing entire system will all different programs working together correctly

CASE (Computer Assisted Software Engineering)

complete tasks like generating test data or creating test reports

Installation

product needs to be installed and implemented; usually involves conversion from old to a new system

Methods of Installation/Conversion

Direct cut-over; Parallel; Phased; Pilot

Direct cut-over

old system completely dropped and new system completely installed; must make sure new system fully works and that users are fully trained

Parallel

operating the two systems together for a period so that the old system is operational for backup; allows major problems in new system to be corrected without loss of data and users have time to learn how to use

Phased

gradual introduction of the new system while old system is slowly discarded; usually used when new system is still in development and makes conversion more manageable for big businesses

Pilot

new system is just installed for a small number of users where they can evaluate and learn the program and once it is good they install it for everyone; can also be seen as the final testing of the product

Maintenance

final stage that is ongoing process of correction and refinement as to continue to meet requirements from users; includes fixing any bugs or upgrading to enhance functionality or changing requirements

Maintainability

measure of how easily a solution can be maintained

Why change the software?

bug fixes; existence of new hardware; integrating new software (e.g. AI); requests from users on changes

Computational thinking

understanding how to break down a task (decision making process; identifying problems and breaking them down to smaller parts)

Variables

named containers that store data in your programs (can hold different data types)

Control structures

Sequence and Selection and Repetition

Sequence

plays code line by line following a process

Selection

Ask a question that has two options and then plays the code due to the chosen option

Repetition

repeating an action over and over (loops)

Snake case

name_name

Pascal case

NameName

Camel case

nameName

Integer

whole negative and positive numbers

Floating point

positive and negative decimal points

String

word or phrase

Boolean

yes; no; true; false

Data dictionaries

ensures all members of development team are aware of what has been used; their data types; storage size; display size and format; scope of usage and other details

What's included in data dictionaries

Variable name; data type; format; number of bytes; size of display; description; example; validation

Format (data dictionary)

e.g XXNNN = MS255

Number of bytes (data dictionary)

mostly all 1 byte each

Size of display (data dictionary)

characters that appear on screen

Description (data dictionary)

purpose of the variable

Example (data dictionary)

what might be stored at given time

Validation (data dictionary)

the range of allowed variables

Types of errors in code

Syntax; Logic and Runtime

Syntax errors

involves misspelling words or forgetting to indent or add symbols to code

Logic errors

code works but doesn’t give correct results

Runtime errors

program works but then crashes while running it

Mathematical operators

Add (+) Minus (-) Multiply (x) Divide (/)

Logical operators

ADD (x && y)(only true when both are true) OR (x || y)(true when either or both are true) XOR (x ^^ y)(Only true when one of them are true) NOT (!x)

Decision trees

acts as a flowchart that shows how a series of decisions can lead to different outcomes

Pseudocode rules

keywords in capitals; every structural element has and end pair; indenting like normal; a subroutine can be referred to in an algorithm by its name

Flowchart symbols

subprogram; input or output; terminator; process; decision

Subprogram flowchart

rectangle with two lines on the sides

Input/output flowchart

slanted square

Terminator flowchart

bean shaped

process flowchart

rectangle

Decision flowchart

diamond on its side

Arrays

example of a data structure that allows us to store multiple values in one single variable

Index of an Array

identifiable position of values (e.g. position 0 or 1)

Desk check

manual process used to test and algorithm or code by working through it step by step with sample inputs

Why use a desk check

ensures the logic of the program works as expected before running on a computer and helps you understand the flow of your code

Writing a desk check

create a table with a column for each variable used and then follow the code line by line entering any changes in variables into the table

Subprograms or subroutines

when a function is called inside our main function

Functions in pseudocode

underline the name

Why we use functions

Avoid repeating code; break up complex programs into smaller pieces

Local variables

when we create a variable inside a function

Arguments

values passed during a function call

Parameters

mentioned in the function definition

Modular design

approach used in software development involving the use of decomposition to break down complex problems into smaller parts like modules or objects; classes; subroutines

Benefits of modular design

code reusability; ease of maintenance; enhanced collaboration; scalability; improved testing code readability