SOFTWARE DEVELOPMENT FUNDAMENTALS

by: A.J. Grandeza, Co-founder Lean Agenda

Topics1. About Lean Agenda2. About the Speaker3. Expectations4. Core Programming – the basics5. Object Oriented Principles – the essentials6. S.O.L.I.D. Principles7. Industry needs and expectations AND TIPS!

The Lean Agenda• A branch of Lean Consulting PH

• We aim to narrow the gap between school knowledge and industry expectations

• Prepare and educate people on the 21st century skills

About Me• Graduate of Ateneo de Davao, Computer Science 2012

• Over 5 years of software engineering experience, .NET and AngularJS

• Co-founder/CTO of T.H.E. Patrons (ex-CTO)

• Co-founder of Lean Consulting, Lean Agenda

• Microsoft Technology Associate

• I LIKE TO LEARN!

What to expect• Programming Language: C#• Only fundamentals will be discussed• Not your typical what-is-a and this-is-a discussion• Feel free to ask• Feel free to correct the speaker• Feel free to add• Learn something new!

What I except from you• Your attention• Questions!• You have at least little knowledge on programming

Because we won’t just be discussing definitions We will have a why-when type of discussion

Core Programming – the basics• What is a variable?

Holds a value temporarily in a computer memory

• What is a constant? Same as variable BUT cannot be changed on runtime or during program

execution

• What is a data type? Classification of the type of a data – Integer, Boolean

Core Programming – Data types

Why is it important to know the data type?

In simple terms…Variable – is the containerData type – is the type of container

Do you want to put cookies in a tumbler?

No!

Well, technically...• Using the correct data type will save space – in memory, only use

what you need You don’t need to use int for “Age”. Nobody gets 2,147,483,647 years old

• Because you won’t be able to multiply a string… 2 * “2”

• It is an implementation detail

Double vs Float vs Decimal• Precision is the main difference

• Float: 7 digits• Double: 15-16 digits

Both are floating binary point types Faster than decimal

• Decimal: 28-29 digits Floating decimal point types Mainly used in financial solutions Slower than the other 2

Core Programming – Data structures• Arrays• Dictionaries

Arrays• A collection of variables• C# arrays are zero indexed

Dictionaries• A collection of objects that are accessed by using a key• Use dictionary if your indexes have a special meaning besides just

positional placement

Core Programming - Decision Making• If, if-else, if-else-if VS Switch

• Switch is faster (a little) However, this is just a micro-optimization

• Switch is more readable• Use switch if you have many items, if-else if fewer

Core Programming - Repetition• For• While• Do while

When to use for loop?• you can run a statement or a block of statements repeatedly until a

specified expression evaluates to false

• Useful for arrays

• When the number of times is known before hand

• Example: Displaying all data in a list

When to use while?•  executes a statement or a block of statements until a specified

expression evaluates to false.

• When the number of times is NOT known before hand

• Example: when your program is waiting for a form to be completed, it will not save the form

When to use do-while• Almost the same with while BUT is executed one time before the

conditional expression is evaluated

• When the number of times is NOT known before hand AND you want to make sure it will be executed at least once

• Example: Display a question, and if the answer is correct move on to the next question.

Core Programming – Exception Handling• What is an exception?

An exception is a problem that arises during the execution of a program.

• Try identifies a block of code for which particular exceptions is activated

• Catch the place in a program where you want to handle the problem

• Finally is used to execute a given set of statements, whether an exception is thrown or

not thrown

• Throw is used to signal the occurrence of an anomalous situation (exception) during the

program execution

Core Programming – Exception Handling• A try-catch structure doesn’t prevent the exception from being

thrown, it simply gives the developer a chance to keep the program from crashing.

• When to use? When you are trying to do something that may not work

• When not to use? To hide problems happening in your code

• Demo

Object Oriented - Principles• What is OOP?

Is a programming paradigm based on objects

• Is it useful? Why? Code reusability Provides clear modular structure for programs Software components can be easily adapted and modified

• What are its disadvantages? Over complication Complexity in understanding “established” code – especially for beginners Prone to code spaghetti

Classes• Can be reused

• It’s like a blueprint

• Includes attributes and behaviour

Abstraction• Exposing essential feature

• Hides irrelevant detail

• Process of identifying common patterns that have systematic variations

Encapsulation• Hide implementation details• Creates a black box• Behaviour can be exposed through interfaces• Data members cannot be directly changed• Encapsulation is implemented by using access specifiers

Private Public Protected Internal Protected Internal

Inheritance• Data & behaviour taken from another class

• Concept of super and sub class

• Provides base functionality for similar objects

• Allows for code re-use

• Use the “is-a” test if it’s appropriate to use

Polymorphism• Poly = multiple

• Morph = to change

• Polymorphism = multiple forms or changes

• Behaviour change

• Virtual methods and overriding

Abstract Class VS Interfaces• Abstract class

Cannot be instantiated Must be inherited from May be fully implemented, partially implemented or not implemented at all

• Why do we need abstract classes? To provide some sort of default functionality Affects all derived classes if there are changes on the base class

Abstract Class VS Interfaces• Interface

Totally abstract set of members No implementation, contains only signatures Represents a contract In real world, a medium to interact with something

• Why do we need Interfaces? Multiple inheritance support Used in service contracts Loose coupling Modularity

S.O.L.I.D. Principles• What is S.O.L.I.D. ?

• Basic principles which help you create good software architecture• Acronym for

Single Responsibility Principle Open Closed Principle Liskov Substitution Principle Interface Segregation Principle Dependency Inversion Principle

Single Responsibility Principle• A class should have one responsibility only

• Separation of concern

• A class is not a swiss knife

• Demo

Open Closed Principle• Should be open for extension but closed for modification

• Demo

Liskov Substitution Principle• objects in a program should be replaceable with instances of their

subtypes without altering the correctness of that program

• Demo

Interface Segregation Principle• many client-specific interfaces are better than one general-purpose

interface

• Demo

Dependency Inversion Principle• Depend on abstractions, not on concretions

• Demo

What to expect in the real world• “If you think teachers are tough, wait till you get a boss” – Bill Gates

• Do not expect any training

• Be ready to read, read and read

• If you get bored easily on tedious work, programming is for you!

What to learn & how to improve• If you’re a beginner, master one programming language• After, strategically choose another language• Master SQL. Everything is all about data.• Learn Version Control, it’ll save a lot of time and plus points on

applying for work!• Constantly challenge yourself• Join GitHub, StackOverflow• Don’t be lazy, always follow best practices until it becomes a habit• Constantly learn new things• Always ask why

Any questions?

•“ Any fool can write code that a computer can understand. Good programmers write code that humans can understand. ” - Martin Fowler

References• http://stackoverflow.com/questions/618535/difference-between-decimal-float-and-double-in-net• https://msdn.microsoft.com/en-us/library/cs7y5x0x%28v=vs.90%29.aspx• http://csharpindepth.com/Articles/General/FloatingPoint.aspx• https://msdn.microsoft.com/en-us/library/aa288453(v=vs.71).aspx• http://programmers.stackexchange.com/questions/139052/dictionary-vs-list• https://msdn.microsoft.com/en-us/library/ch45axte.aspx• http://wiki.tcl.tk/13398• https://standardofnorms.wordpress.com/2012/09/02/4-pillars-of-object-oriented-programming/• http://www.c-sharpcorner.com/UploadFile/d0e913/abstract-class-interface-two-villains-of-every-

interview/• http://www.c-sharpcorner.com/UploadFile/d0e913/abstract-class-interface-two-villains-of-every-intervi

ew756/

• http://www.c-sharpcorner.com/UploadFile/yusufkaratoprak/difference-between-loose-coupling-and-tight-coupling/

• http://www.codeproject.com/Articles/703634/SOLID-architecture-principles-using-simple-Csharp