01 - [Classes] C++ Intermediate Programming Tutorial

Summary

This tutorial provides an introduction to classes in C++ programming. It explains what classes are, how to create them, and their key components such as attributes (like age, name) and methods (like walking or driving). The video walks through creating a simple 'Human' class with attributes and member functions, showing how to declare and define these. It also covers access modifiers (public, private, and protected) and their importance in controlling visibility. Finally, the instructor demonstrates object creation and method usage, helping beginners grasp the fundamentals of object-oriented programming in C++.

Takeaways

• 📚 A class in C++ is essentially a structure used to store data, defined by a header and C++ file.
• 📝 To create a class, you can either add a new item or class in Visual Studio, then name the class and its files.
• 👥 Classes represent real-world or conceptual objects with attributes (like age or name) and methods (like walking or driving).
• 🔧 Methods in a class are functions that define what actions an object can perform, and attributes define its properties.
• ⚙️ Inside a class, there are access modifiers: public, private, and protected, which control access to attributes and methods.
• 🚶 Methods in the class can be created within the header file or defined in a separate CPP file by including the class name with two colons (::).
• 👤 Objects are instances of classes, meaning that a class defines the blueprint, and an object represents an actual instance (e.g., John is an object of the class Human).
• 🛡️ By default, class members are private unless specified otherwise with access modifiers.
• 📝 Methods inside a class are referred to as member functions, and attributes as member variables.
• 💡 Classes are versatile and can represent anything, from real-world objects like humans to conceptual ideas like rocks or mathematical objects.

Q & A

What is a class in C++?

A class in C++ is a structure that represents data. It serves as a blueprint for objects, allowing you to define attributes (data) and methods (functions) that represent real-world entities or conceptual models.

How do you create a class in C++?

To create a class in C++, you can either manually add a header file and a C++ file with the same name or use Visual Studio to create a class through the 'Add Class' option. The class declaration starts with the 'class' keyword followed by the class name.

What are the attributes and methods of a class?

Attributes are the data or properties that define a class, such as age or name. Methods (or member functions) are the actions that objects of the class can perform, such as 'walk' or 'drive'.

What is the difference between functions and methods in C++?

In C++, functions that are declared outside of a class are called functions, whereas functions declared inside a class are called methods or member functions.

What is the purpose of access modifiers in a class?

Access modifiers in a class (public, private, and protected) determine the visibility and accessibility of the class members. Public members can be accessed by any code, private members can only be accessed within the class itself, and protected members can be accessed by the class and its derived classes.

How do you access the attributes or methods of a class object?

You can access the attributes or methods of a class object using the dot operator (.). For example, if you have an object 'John' of the class 'Human', you can access the age attribute using 'John.age' and call a method like 'John.walk()'.

What is the difference between a class and an object in C++?

A class is a blueprint or template that defines the structure and behavior of objects, while an object is an instance of a class. For example, 'Human' is a class, and 'John' is an object created from that class.

What are the default access levels for class members in C++?

By default, the members of a class in C++ are private. If no access modifier is specified, the members are treated as private, meaning they are only accessible from within the class.

How do you separate class declarations and definitions?

Class declarations (including the definition of member functions) are typically placed in a header file (.h), while the implementation or definition of member functions is done in a corresponding .cpp file. This separation improves code organization and maintainability.

What are the key things to remember when working with classes in C++?

Key points include understanding attributes and methods, using proper access modifiers (public, private, protected), recognizing the difference between classes and objects, and knowing how to initialize and use class objects.

Outlines

00:00

🛠️ Introduction to Creating Classes in C++

In this section, the speaker introduces the concept of classes in C++ and how to create them within a project. A class is described as a structured data type, with a focus on the practical steps of adding a class in an IDE. The speaker explains how to create a new class by either manually adding a .cpp and .h file or using IDE tools to generate them. Additionally, there's a mention of base classes and virtual destructors, which are ignored for simplicity. Finally, a brief troubleshooting guide for common errors, such as missing entry points, is provided.

05:03

👤 Defining Class Attributes and Methods

This paragraph explores how classes represent real-world or conceptual entities through attributes (data) and methods (functions). Using the example of a 'Human' class, attributes like age, name, and surname are introduced, emphasizing how these traits are common to all humans. The speaker clarifies the difference between attributes (such as age) and methods (like walking or driving), explaining that methods define what an object can do. The explanation also highlights C++ syntax, distinguishing between functions outside of a class (functions) and those inside a class (methods or member functions).

10:04

🔒 Understanding Public, Private, and Protected Access Modifiers

In this section, the concept of access control within a class is introduced. The speaker explains the importance of the public, private, and protected segments of a class, comparing them to 'private parts' of a human that are not visible to others unless specifically shared. Public members are accessible to other classes and objects, while private members are hidden. The speaker also touches on the 'friend' keyword and protected sections, which allow visibility under inheritance or among friends. The paragraph sets the stage for understanding encapsulation and access modifiers, which are vital for class design.

15:07

📋 Class vs. Object and Initializing Objects

This part of the tutorial dives into the difference between a class and an object, explaining that a class is essentially a blueprint, while an object is an instance of that blueprint. Using the 'Human' class example, the speaker demonstrates how to create and initialize an object, assigning values to its attributes and calling its methods. It covers basic object initialization and the dot operator for accessing attributes and methods. The speaker also emphasizes that classes are data types, much like primitive types such as int, and objects are instances of these types.

20:07

🧠 Recap: Classes as Real-World Representations

The final paragraph wraps up the tutorial, reinforcing the idea that classes in C++ are representations of real-world entities or conceptual ideas. The speaker highlights the flexibility and possibilities that classes offer, noting that any object or concept we can imagine can be represented using a class. They briefly mention advanced concepts like constructors, destructors, operator overloading, and the 'Rule of Three/Five,' which will be discussed in future tutorials. The tutorial concludes with a call to action for viewers to ask questions, like the video, and subscribe for future content.

Keywords

💡Class

A class in C++ is a blueprint or template for creating objects. It defines the structure of objects, including attributes (data) and methods (functions). In the video, the instructor explains that a class is a representation of something in the real world, like a human or a conceptual thing, and shows how to create one by defining attributes like age and methods like walk.

💡Attributes

Attributes are data members or variables that define the properties of a class. In the context of a 'Human' class, attributes could include age, name, or surname. These are specific to each instance of the class, representing unique characteristics of an object. In the video, the instructor uses examples like int age, string name, and string surname to define the attributes of the Human class.

💡Methods

Methods, also called member functions, are actions or behaviors associated with a class. In C++, they are functions defined inside the class. For example, in the 'Human' class, methods like 'walk' and 'drive' represent actions that a human can perform. The instructor demonstrates how methods are written within a class and are invoked using an instance of that class.

💡Public

Public is one of the access modifiers in C++ classes that determines the visibility of class members. Public members can be accessed from outside the class. The video highlights the importance of public access in allowing other classes or code to interact with certain methods or attributes of a class, such as accessing the age of a human or invoking the walk method.

💡Private

Private is another access modifier in C++, which restricts access to class members. Private members can only be accessed from within the class itself, not from outside. The instructor explains that just as humans have private parts that are not shown to everyone, classes can have private sections, which are hidden from external access.

💡Object

An object is an instance of a class, created based on the class's blueprint. In the video, the instructor refers to 'John' as an object of the Human class. The object holds the actual data for its attributes (like age = 24 for John) and can perform actions using the methods defined in the class (like John.walk()).

💡Constructor

A constructor is a special method in a class that is automatically called when an object is created. While not covered in detail, the video hints at the importance of constructors in initializing class objects. Constructors are typically used to set default values or perform setup actions for an object when it is instantiated.

💡Encapsulation

Encapsulation is the concept of bundling data (attributes) and methods (functions) that operate on the data into a single unit, which is the class. The video emphasizes this idea by showing how a class can hide its internal data (using private attributes) while exposing certain functionalities (public methods) to the outside world.

💡Inheritance

Inheritance is an advanced object-oriented concept where a class (child class) inherits properties and behaviors (attributes and methods) from another class (parent class). Though inheritance is mentioned briefly in the video as a topic for future videos, the instructor refers to the concept when talking about classes being 'extended' with new features.

💡Access Modifiers

Access modifiers control the visibility of class members in C++. The three main access modifiers are public, private, and protected. In the video, the instructor explains how public members are visible to everyone, private members are hidden, and protected members are reserved for derived classes. These modifiers help implement encapsulation and control how data and functions are accessed.

Highlights

Introduction to C++ classes: a class is a structure in a C++ file that holds data.

The process of creating a class in C++ involves either adding a new item or right-clicking the project to add a class.

Classes represent real-world objects or conceptual things inside a program, allowing you to work with them efficiently.

Attributes (e.g., age, name, surname) and methods (e.g., walk, drive) are two core components of a class.

The difference between functions and methods: inside a class, functions are called methods, which can interact with class attributes.

Use of access modifiers in C++: public, private, and protected segments control visibility and access to class members.

Private members are hidden from outside classes, and public members are accessible, which allows control over class structure and behavior.

Objects are instances of classes, and creating an object (e.g., John) from a class (e.g., Human) enables access to class attributes and methods.

Object initialization involves creating variables using class types, similar to creating data types like integers.

C++ classes use the dot operator to access attributes and call methods on objects.

Access modifiers and their importance: public methods are accessible everywhere, private parts are hidden, and protected parts can only be accessed by child classes or friends.

Basic concepts of inheritance and friend functions in classes: topics to be covered in future tutorials.

Introduction to encapsulation: keeping class attributes private to prevent outside access, ensuring better data security and structure.

Classes are templates for creating objects, but the class itself does not hold any data until an object is instantiated.

Final remarks on the importance of C++ classes for representing real-world concepts and the possibilities they provide in programming.

Transcripts

hey guys and gals this mean your ex and

welcome to intermediate C++ programming

tutorial so in today's video we'll be

talking a little bit about classes and

what they are and what they were present

and how we can work with them the

entirety of it okay so before we get

right into it

let's just open our project up and I

want to show you something so the way

you create a class and basically what a

class is it's just a header on a C++

file that's all it is it's a structure

that data is stored in no special

structure that you make so the way to

create a class is either you go by add

new item added 800 CPP have them have

the same name or easier than that just

right-click on any of these folders or

the project and add new item or add

class down below and then you can just

click on this class name it here or

don't it doesn't matter and then you can

name it here as well so I can name it

something like our first class and as

you can see I'm doing an in camel case

weight but the camel case is a bit

different I'm using capital in the first

letter now there is a base class here

that and we don't give a damn about

there's a virtual destructure and inline

thing you also don't care about that so

what I'm going to say in line there's no

CPP there shoulders structure is for you

know the ones that usually have usually

are to be inherited from but we don't we

don't care about that so just yet and

when you do that you can then this tab

gets open and you know you can do

whatever you want we still don't care

about that all right so we have the name

about name of our class here let me hit

OK as you can see I have two files but

if I try to build my application I'm

definitely going to get an error the

reason to that is I don't have an entry

point as you can see come on dude just

doing two files so as you can see it's

giving me the error that saying entry

point must be defined so

I'm just gonna go ahead and create yet

another C++ file source let CP be big

enough and do void main or intimate

doesn't doesn't really matter so just

some simple like that all right run

it as you can see one succeeded no all

good all dandy so now let's get into our

class I'm just gonna do it I'm sorry

double tap like this right here I'm

sorry for the coughing I've caught a

cold so yeah right so this is our class

this is the entirety of our class now a

class is nothing but a representation of

something that exists in the real world

so whatever we want to represent

something that exists in the real world

inside our program we use a class either

something that exists in the real world

or a conceptual thing all right so our

first class I'm just gonna go ahead and

delete this and this and then I'm going

to be renaming this our first class

class so the way you create a class is

quite simple all you need to do is write

class and then now there are two ways of

course you can use a snippet class tab

and it'll generate the entire thing for

you or we can just write a name I'm

going to write human class human so

human is a is an ideal thing in our

world we are all humans we have

different attributes but we are all

human right now every class can have two

things classes can have attributes and

members they can have I'm sorry

attribute some methods so attributes are

what define us okay like eye color age

or you know hair color or nationality or

whatever the hell and methods or what we

are capable of doing driving a car for

for instance so I can have an attribute

let's say I have an int named H

just like that I have another 8 or

rather a yeah it's why not I have

another aunts name mm-hmm what do I have

yeah let's say I have a C type string

name has a C type string surname another

C type string I don't know that's a SAN

whatever the hell

alright so H name surname that's the son

whatever you can think of so these are

what I have these are different every

human has these all right unless you

live and like you know in jungle or

something you don't really have SSN then

but let's just actually do you know take

that out so every human has an age every

human has a name every human has a

surname that's that's a general thing

everybody has this name the entire world

Oh No one way or another they all have

these they all have things that can be

placed into these places or can be

defined as name and surname now this is

a basic human all right this is a schema

for the human all right

but it's not any human now we will get

to that sound so it's just a scheme for

a human or any human that you want to

have will be obeying this structure this

this data structure now it can also the

class can also have functions or methods

rather so functions outside a class are

called functions is an important note so

this is a function but inside the class

we call them methods all right so method

is here function is there an attribute

is here all right so these are

attributes these guys inside this guy is

method or member functions all right so

they're they're either called methods or

member functions and and we're going to

learn about you know pointers to members

functions and pointers to functions and

all that good stuff

okay so methods now every human can also

do things all right for instance we can

do something like what every human can

walk

void let's say drive now every human can

learn to drive

alright so every human can walk every

human can drive a sexually returned a

bull to see if driving was successful if

it was successful I will return the

truth or if walking is successful if

you're like one-year-old you probably

can't walk alright

so easy peasy just like that we create a

class it has attributes

it has functions no methods or member

functions now the way you create a

function as you can see it's already

empty alright so you can either do it

like this or in a better way you can

bring the definition to the CPP class so

the dot H classes as usual for

declaration and the dot CPP is for

definition the way you do that turn two

ways the easy way and the hard way

Rho the kind of hard right son sorry

it's not really that hard so what you do

that is you first include this guy you

have to and then you do return type name

of the function just how you do it a

normal way but the difference is you

need to add the name of the class with

two columns before the name of the

function and that's it there you have it

you have your entire thing up and

running as you can see the green zigzag

line is gone it's no longer there it's

still here because we haven't

implemented drive yet but I yeah so

let's just return true just to avoid any

errors now that was the slightly harder

way which is really not that hard

the easier way if you're using visual

studio is to just hold ctrl press dot

and then enter and there you have it

already there for you and this is how

you create functions and then thing you

can call those functions which we will

get to pretty soon right but before we

get to any functions what I want to talk

to you about or three things all right

private protect it

and public all right so these are

sections or rather segments of our class

that we determine what to be Oh

should they be visible - or whose whom

should they be visible - for instance

every class has a public section or a

you know yeah public section has a

protected section in the private section

just like us humans who have public

parts and private parts we don't really

show our private parts to any everybody

you only show them to friends which

we'll talk to well which we will talk

about pretty soon you can use the

keyword friend I've used it so in

several of my projects not really I

don't really I'm not really a fond of it

I'm not really fond of using that

keyword but you got to do what you got

to do boy so yeah anyhow public section

we have public we have private and we

have you know protect it so protected

right now the access these determine who

can access whatever comes under it all

right so all these guys all of these

guys are private I'm sorry I'm public

because they're determined they're

defined under a public segment if they

were to take these guys out put them

here which is a part of my standard

public should always come after private

now everybody in C sharp everybody who

has coding in C sharp is like yeah we

determine the privates first then public

comes but honestly if someone is reading

your code didn't really give a damn

about your private things in the class

no they really don't I want to see what

they can access and we'll get there

don't worry about it

so public is what others can see and

what others means I mean other classes

than human right outside of human what

can see these everybody because it's

public what the children can see now I'm

just gonna hold pull this star here

we're gonna talk about this guy any

inheritance don't worry about it

this is a to do video alright this is

not not not for now this is for later

and then there's the private part

what no one can see alright nobody

nobody's gonna see your private parts

right almost our friend France can see

which we will talk about in another

video not just yet so this will be for

another video as well as a to do to do

video alright so friends or Frankie wart

is also a to do video children is for a

to do videos for the inheritance so this

guy it's gonna be for the front Huard or

rather friend keyboard and this guy is

gonna be for in hairy tendons topic

alright so no it's not like that alright

so these are the these are what we call

access modifiers and by default classes

don't have access modifier this guy

right here means it's private so if you

start a class by private you basically

I've done nothing to change anything

by default whatever you put under this

guy right here means it's private

yeah just like that easy peasy alright

so this was a super basic introduction

to class right we will be talking about

constructors destructors

copy constructors semantics

you know operator overloading you know

all that goes to the rule of all the BS

rule of 3 or 5 rai you know all that

good stuff

soon enough not just yet all I want you

to know is that you have classes all

right in classes represent things that

we think that are human or I mean death

damned things that can be found in the

real world

alright so if you find the rock you can

probably make a class of rock like this

so plus rock I'm not doing Johnson I'm

sorry

so we have public public thank you any

problem has like unit weight and another

and maybe yes I don't know all right if

you really do

physics yeah you can do something like

that but it doesn't really matter and um

yeah we'll get to encapsulation where we

talk about that these guys these members

they should always all the damn time be

on a private just don't don't worry

about it all right

so there was a reason I put them here

okay so public protected private you

know even just like us humans this human

also has public and private parts and we

put whatever reason Friday first like

like the length Heights yeah yeah I just

wrote that more simpler hi all right I

just private just doesn't a length of

thing length of the height so yeah

whatever so yeah we have privates we

have protected and protected in public

we I think I'm over explained it in a

lot alright so how the hell do we use a

class first off we need to include it we

need to include the header that is

defined in so just like I included

something like string which is also kind

of a class all right those string is

this kind if a class is a kind of a

Microsoft class see it's it's a using

basis string and basis change of peek it

you know class spaces string so yeah

it's kind of a class all right now it's

a very different kind of class the

template passed but we don't worry about

that but yeah so string is basically a

class alright and just as we use the

header to use a class we include our

first header I'm sorry our first header

like this to be able to use whatever is

inside it all right easy peasy quite you

know simple now the way we use it is if

you remembered if you remember we want

to create variables let's say I want to

create an int I say int I equals five

all right simple easy peasy or just

easier than that and I I have created an

integer after I I mean I'm half the

neighbor the name I all right create an

integer named I simple and easy

same thing with a class so we create a

class you are creating nothing more than

a data type this guy right here is

nothing more than a goddamn data type so

I can just say human age and that's it

and I hum an H all we have to do is that

all right we don't care about this guy

right here we don't care about the equal

or the assignments I don't care about

the initialization just yet we will talk

about that in another video for now all

we care about is this guy

all right so human H whatever and I fold

F so just as we create some of these

guys we can create one of these guys and

do you make notes classes starts with or

at least in Maya

standard classes start with a capital

letter camel case and capital letters

and that's how we create a class now how

do we use a class so as you may have

already noticed classes have methods and

members now just for the sake of this

tutorial I want to put them here okay

just to make it simpler and I'm gonna

take out wall a drive away so it's just

gonna have an age and it's just gonna

have one method walk all right

one method one member and this guy's

gonna return the ball so the way you do

it is hit H dot and with the dot

operator you can see these two guys

right here and yes dot is an operator so

H dot you can do H equals ten now eight

age in our well it's bad naming so let's

just do human with capital e so let's

just make it a better one

so John all right John today H is like

24 all right John is 24 years old John

can also walk simple as that

so this is how we assign data to this

guy and this is how we use functions and

will rather call functions we can also

use that so I'll just say anti or rather

but I already have my so our equals John

dot H I'm sorry

quite simple quite easy so I'm just

using an attribute inside John all right

that came out pretty bad and that I can

call a function or a rather member

function within the class of John within

the class of human but an instance of a

human plat of our human class John okay

so here's the thing that a lot of people

make mistakes when they're first

learning about classes so there are two

things there is a class and there's an

object all right this guy right here is

what we call a class it's like an empty

form that we need to fill in okay it's

like a scheme it's like a blueprint like

okay if you want to have a human you're

human needs to have these two right

that's basically it

now I want to create a human so I create

a human and the name of the human is

John now John is an object of the class

type human just like int is an object of

type int well not really but they are

kind of the same thing all right I'm

sorry if I say like this these are

teaching mistakes I have to make them

just so you can understand it easier but

I don't worry about it

they're all just teaching mistakes I am

intentionally sometimes making mistakes

I like in the case of pointers the key

thing is it's not really a bug in the

box but I explain it like that so you

understand it better any help so this is

a class this is an object all right a

class you can't really you can't really

do something like this just yeah

generally do dot dot walk it's just

gonna give an error you can't even do

something like that it's still gonna

give you an error there are reason to it

there's a reason to it and I will talk

to you about that a bit more is a gap we

will talk about that operator soon

enough not just yet so yeah this is our

object this is a class quite easy quite

simple and the way we initialize classes

is kind of different couldn't do

something like this and then we have

initialized our class

so if I just run it I'm not gonna posit

or anything you can just see that it

builds correctly and it goes through

with ease come on dude thank you my dude

oh there we go

so as you can see there is no error

there everything is good everything is

easy we just have created a value type

of John you're gonna use that pretty

goddamn clean all right and that's

basically it for this video I hope you

understood what classes are all about

pretty goddamn easy and simple they're

just a representation of something in

the real world or some conceptual thing

that we want to talk about or rather we

want to bring in our code like say if we

have an object class and that object

class has a math or I'm sorry in mass or

a density integer or a calculate density

function or whatever so possibilities

are endless if we can't imagine it you

can put it in a class simple as that and

you can just represent it like this

anyhow that's been it for this video

guys I hope you enjoyed if you have any

questions do ask them in the comments

below if you have if you enjoyed this

video do leave a like and maybe even

subscribe that would help a lot thank

you very much I will see you in the next

one