4 | PHP Variable and Data Type Tutorial | 2023 | Learn PHP Full Course for Beginners

Summary

This video tutorial delves into PHP basics, focusing on syntax and variable creation. The instructor guides viewers through setting up a local server with XAMPP, navigating to the 'Local Host' to view websites, and embedding PHP within HTML. The concept of variables is introduced as memory locations for data storage, with examples of scalar data types like strings, integers, floats, and Booleans. The video also touches on arrays and object types, emphasizing best practices for variable naming and initialization. Practical examples illustrate how variables can be used and assigned within PHP code, offering初学者 a foundational understanding of PHP programming.

Takeaways

• 😀 The video discusses PHP syntax and how to create variables and understand data types.
• 💻 To view a website in a browser, ensure the editor is open, XAMPP is running with Apache and MySQL servers started, and then navigate to 'Local Host' in the browser.
• 📝 Embedding PHP within HTML is demonstrated, highlighting the use of PHP tags and the `echo` statement to output data.
• 🔑 Variables in PHP are introduced as memory locations that store data, likened to labeled boxes containing items.
• 🛠️ Variables are declared with a dollar sign (`$`) and are named to reflect the data they hold, adhering to naming conventions for readability.
• 🔡 Data types covered include scalar types (string, integer, float, Boolean), which hold single values, and the concept of default values for each type when not initialized.
• 📊 Arrays are mentioned as a data type that can hold multiple values within a single variable, with examples of declaring and initializing arrays.
• 🚫 The video cautions against declaring variables without initialization to avoid potential errors and suggests assigning default values instead.
• 🔑 The video briefly introduces object types, relating them to classes and instantiation, though noting they are not the focus for beginners.
• 📚 It reassures viewers that it's normal to feel overwhelmed with new information and emphasizes the importance of practical experience for learning and retention.

Q & A

What is the first step to view a website in a browser when using an AMP stack like XAMPP?

The first step is to have your editor open, which is essential for viewing and editing your website's code.

Which two servers need to be started in XAMPP to run a PHP website locally?

You need to start the Apache and MySQL servers in XAMPP to run a PHP website locally.

How do you access your local PHP website in a browser?

You access your local PHP website by typing 'Local Host' in the browser's URL bar.

What is the significance of the dollar sign ($) in PHP when creating variables?

The dollar sign ($) is used to declare a variable in PHP, indicating the start of a variable name.

What is the purpose of the 'echo' statement in PHP?

The 'echo' statement in PHP is used to output data to the browser, allowing you to display content on the webpage.

Why is it a good practice to end PHP statements with a semicolon even if it's the last statement?

Ending PHP statements with a semicolon is a good practice because it ensures consistency in your code, and it doesn't hurt to do so even if it's the last statement.

What is a variable in the context of PHP programming and how is it represented?

A variable in PHP is a memory location that stores data, represented as a 'box' with a label to easily reference and manipulate the data it contains.

What are scalar data types in PHP and give an example of each?

Scalar data types in PHP are data types that contain a single value. Examples include strings (text), integers (whole numbers), floats (numbers with decimal points), and Booleans (true or false).

How do you declare a variable in PHP without assigning a value to it?

You can declare a variable in PHP without assigning a value to it by using the dollar sign followed by the variable name, but it's recommended to always initialize variables to avoid potential errors.

What are the default values for different data types in PHP when a variable is declared without an initial value?

The default values in PHP for different data types when a variable is declared without an initial value are: strings default to an empty string, integers and floats default to zero, Booleans default to false, arrays default to an empty array, and objects default to null.

How can you use a variable to output data within an HTML element using PHP?

You can use a variable to output data within an HTML element by embedding PHP tags within the HTML and using the 'echo' statement to output the variable's value.

Outlines

00:00

💻 PHP Syntax and Variables Introduction

The paragraph begins with a recap of the previous video's discussion on PHP syntax and transitions into an exploration of variable creation and data types. The speaker suggests using an editor to write PHP code and emphasizes the practical experience of coding. They guide viewers on how to start a website using XAMPP, detailing the steps to launch Apache and MySQL servers and access the website through a browser. The explanation continues with embedding PHP within HTML, illustrating the use of PHP tags and the 'echo' statement to output data. The speaker also touches on the importance of semicolons in PHP, even when they seem optional. The paragraph concludes with a practical demonstration of mixing PHP and HTML to dynamically generate content on a webpage.

05:02

📝 Understanding Variables and Naming Conventions

This section delves into the concept of variables in PHP, likening them to labeled boxes that store data. The speaker simplifies the idea by suggesting that variables are used to label and access data easily within code. They explain how to declare and initialize variables using the dollar sign ($) and provide an example of creating a string variable. The paragraph also covers variable naming conventions, advocating for a lowercase first letter followed by capitalized letters for subsequent words (camelCase). The speaker advises against starting variable names with numbers or special characters, except for underscores. The discussion serves as a foundation for understanding how variables are used in PHP to handle and reference data within applications.

10:03

🔢 Exploring Data Types in PHP

The speaker introduces the concept of data types in PHP, focusing on scalar types that include strings, integers, floats, and Booleans. They explain that scalar types hold single values and provide examples for each type, including how to declare and initialize them. The paragraph distinguishes between data types by showing the difference between a string with quotes and a number without quotes, emphasizing the importance of type distinction in PHP. Boolean values are also introduced with the values 'true' and 'false'. Additionally, the speaker briefly mentions arrays and objects, describing arrays as variables that can hold multiple values and objects as instances of classes, although the latter is noted as an advanced topic for future discussion. The paragraph aims to familiarize viewers with the basic data structures in PHP.

15:05

🧩 Practical Usage of Variables in PHP

In this part, the speaker addresses potential confusion about arrays and objects, reassuring learners that detailed explanations will come later in the course. They introduce the concept of variable instantiation, explaining how variables can be assigned default values based on their context if not explicitly initialized. The speaker outlines the default values for different data types: empty strings for strings, zero for numbers, 'false' for Booleans, empty arrays, and 'null' for objects. The paragraph concludes with a practical example demonstrating how to use variables within HTML and PHP to display dynamic content on a webpage. The speaker also shows how to assign one variable to another, creating a copy of the data. The paragraph ends with encouragement for learners to practice PHP and to not be overwhelmed by the amount of new information, promising more practical examples in future lessons.

Keywords

💡PHP

PHP is a server-side scripting language designed for web development. It is used to create dynamic web pages and manage server-side logic. In the video, PHP is the central theme as the instructor discusses its syntax, variables, and data types, which are fundamental to understanding how to write PHP code. The script mentions embedding PHP within HTML to create dynamic content on a website.

💡XAMPP

XAMPP is a free and open-source cross-platform web server solution stack package. It integrates Apache, MySQL, PHP, and Perl, making it a popular choice for local web development. The script describes starting XAMPP to run a local server, which is necessary to view PHP websites in a browser during development.

💡Variables

In programming, a variable is a storage location paired with an associated symbolic name, which contains some known or unknown quantity of information referred to as a value. In the video, variables are introduced as a way to store and manage data within PHP. The instructor uses the analogy of a box with a label to explain how variables hold and reference data.

💡Data Types

Data types in programming define the classification or category of data, determining what kind of data can be stored in a variable. The video script explains several data types in PHP, including scalar types like strings, integers, floats, and Booleans. Understanding data types is crucial for managing different kinds of data within PHP scripts.

💡Echo

The 'echo' statement in PHP is used to output one or more strings. It is a fundamental concept in PHP for displaying content in a web browser. The script uses 'echo' to demonstrate how to display the content of variables within HTML elements on a webpage.

💡HTML

HTML (Hypertext Markup Language) is the standard markup language for creating web pages and web applications. The video script discusses embedding PHP within HTML to create dynamic web content. HTML provides the structure, while PHP adds functionality and interactivity.

💡Scalar Types

Scalar types in PHP refer to data types that store a single value. The script mentions string, integer, float, and Boolean as examples of scalar types. These are the basic building blocks for handling simple data in PHP, and the video provides examples of how to declare and use them.

💡Arrays

An array in PHP is a data structure that contains multiple values in a single variable. The script briefly introduces arrays, explaining that they can hold multiple pieces of data, unlike scalar types which hold only one value. Arrays are useful for managing lists or collections of data.

💡Boolean

A Boolean data type in PHP has only two possible values: true and false. It is used for logical operations and conditions. The video script explains that Booleans are used to represent truth values and are essential for control flow in programming, such as in conditional statements and loops.

💡Naming Conventions

Naming conventions are a set of rules for choosing the character sequence used in names of identifiers. In the video, the instructor discusses the customary naming conventions for variables in PHP, such as starting with a lowercase letter and using uppercase letters for the first letter of subsequent words (camelCase). Following naming conventions helps in writing readable and maintainable code.

💡Default Values

Default values in PHP refer to the initial values that variables take on when they are declared without an explicit value. The script explains that different data types have different default values, such as an empty string for strings, zero for numbers, and false for Booleans. Understanding default values is important for avoiding errors and unexpected behavior in PHP code.

Highlights

Introduction to creating variables and data types in PHP.

Practical experience with PHP code by starting a website.

Steps to view a website in a browser using XAMPP.

How to embed PHP within HTML to output content.

The importance of semicolons in PHP statements.

Demonstration of mixing PHP and HTML to create dynamic content.

Explanation of what a variable is in PHP.

Analogy of variables as boxes with labels for data storage.

How to declare and initialize a variable in PHP.

Naming conventions for variables in PHP.

Introduction to scalar data types in PHP.

Understanding strings, integers, floats, and Booleans as scalar types.

The concept of arrays as a data type to store multiple values.

Different ways to create arrays in PHP.

Mention of object-oriented programming with classes and objects.

Default values for different data types when variables are declared.

Advice on always initializing variables to avoid errors.

Encouragement for beginners to not be overwhelmed by the information.

Practical example of using variables in PHP code.

How to assign one variable to another in PHP.

Closing thoughts and anticipation for the next video.

Transcripts

so in the last video we talked a bit

about PHP syntax and today we're going

to talk a bit about how to create

variables and data types now I do think

it's a really good idea that we go

inside our editor in this video and just

talk a bit about this so we have some

practical experience writing vhp code

and with that we do need to actually

start up our website and I thought why

not do that together since that is

something we haven't done yet so what

you need to make sure you do every

single time you want to see your website

inside the browser is first of all you

need to have your editor open which is

step one then you need to make sure

you're opening up xampp so you want to

open up the software make sure you

actually start the Apache and MySQL

server then you want to go inside your

browser and then you want to go into the

URL and type Local Host and when you do

that you can see all the websites that

you have inside your htdocs folder in my

case here I do have two websites you

should not have two you should only have

one so go ahead and pick the one that we

created together in the first episode

and then you can see we have our website

in front of us here and that's the basic

step in order to open up your website

when you're running it inside A7 server

like xampp so now we can go back inside

our index.php and just to kind of talk

briefly about the last episode because I

know some people are a little bit

confused when it came to embedding HTML

and PHP together so if I were to go

inside I can create a regular HTML

paragraph and I can go and create this

is a paragraph and just write some text

inside this paragraph here now what you

can do is you can create the PHP tags so

the opening and closing tags so angle

bracket question mark PHP then you can

say question mark angle bracket so what

I could do is echo which we talked about

is how to Output things inside the

browser I can say this is also a

paragraph and we do need to make sure

remember that semicolon even though

because this is the last statement

inside this particular PHP tag here we

don't technically need to have this last

semicolon but like I said it is best

practice to remember to do it every

single time because it doesn't hurt

anything to do it so let's just go and

do it every single time and when you do

this you can go back inside your website

refresh it and then we can see we have

two pieces of text we have this is a

paragraph and this is also a paragraph

So we have two paragraphs inside our

website and just to show something a

little bit more complicated you can also

go inside existing HTML elements and

create PHP so I can go in between here

and I can open up my PHP tags and then I

can write something additionally in here

so it would have to Echo again because

we need to make sure to Output whatever

we're doing using PHP and I can go ahead

and Echo awesome paragraph

semicolon save this one go back inside

my website and then you can see we've

included this awesome paragraph in here

and this is just to kind of show that we

can mix and match PHP and HTML together

in any sort of way that we want by

embedding it directly inside the HTML

but now this is not what I wanted to

talk about in this video here I do

actually want to talk about variables

and data types because we do have

variables and data types which we use

constantly when it comes to writing PHP

code so this is something we have to

memorize so let's go and talk a bit

about what exactly a variable is now a

variable is when we have a memory

location inside our application that

stores some sort of data which is a very

confusing way for beginners to

understand what exactly a variable is

because a lot of people don't understand

what is memory location and that kind of

thing so instead just for practice here

let's pretend that a variable is a box

and that box has a label so you know

when you're moving into a new house you

put you know some writing on the box

whether it's kitchen utensils or for the

the kids room something so you know

what's inside the box but then you do

also have something inside the Box some

actual data so whenever you grab this

box by referring to the name of the box

then you grab whatever is inside the box

as well and that is technically what a

variable does so when you reference to a

variable you grab the data and it's just

a very easy way for us to refer to data

and label it so we know exactly what the

data is now when it comes to PHP the way

you refer to a variable or the way you

declare a variable is by creating a

dollar sign so if I were to go inside my

PHP tags here I can create a dollar sign

which means that now we are declaring a

variable and then we can call it

something so we can come up with a name

for this variable that we think makes

sense to the data that is inside the

variable so in this case here I could

say that this is a name so I could say

that this is a name and it's going to be

equal to some kind of data so now we're

initializing this variable by assigning

a piece of data to it so in this case

here I could say that it is a string

which we talked about before called

Danny Crossing so now every time I refer

to this variable called name I'm going

to get a value called Danny Crossing so

if I would go below here and just echo

which means that we're outputting

something inside the browser and I can

go ahead and Echo out name or the

variable called name so we need to

remember the dollar sign here if it were

to do this go back inside my website you

can see that we're echoing out Danny

Crossing so in this sort of way we can

create boxes or labels four pieces of

data that we can refer to in order to

better handle data inside our code so in

this case if we create a variable called

name and you can call whatever you want

but now we do also have naming

conventions when it comes to naming

these variables here so in this case you

can see we call this one variable name

but we can also go in and either start

it with a letter or a underscore in

order to name this variable now the

customary thing is to start with a

non-capitalized letter and then make

sure that any other new words inside

this variable name starts with a

capitalized letter so if I were to write

full name instead then we start out with

a non-capitalized F and then a

capitalized n for name so whenever you

have multiple words inside the variable

name then you just make sure the first

letter of that second word or third word

or fourth word is going to be

capitalized and again it's not really a

customary thing you have to follow but

it's it's the way that people do it so I

would recommend doing it the same way so

people don't misunderstand what your

code does or why you named your

variables in this way that other people

don't usually do it and just to mention

it when it comes to any other letters

that isn't the first letter inside the

variable name then you can also go ahead

and create either underscores or you can

create numbers so we can say one but

make sure you stick within letters

underscores or numbers when it comes to

the variable name after the first letter

inside the variable name so now let's go

ahead and delete what we have here and

talk a bit about data types because when

it comes to data types inside PHP we

have many different data types we're not

going to talk about all of them in this

video here since some of them are a

little bit more complex than others but

we will talk about some of the base

types that you have inside PSP the first

one is going to be what is called scalar

types and scalar basically just means

that the variable contains one value to

it and the first example of that would

be we could create a variable that is

called something like string

and a string we did already talk about

what kind of data that is so in this

case here we could say uh Daniel so as

we know already a string is a piece of

text now we do also have numbers so I

can go below here and I can create a

integer or a int and I'm going to go

ahead and name this one a number so we

can just write some sort of random

number here and this is going to be a

value for a integer notice that we're

not using double quotes around the

number because if I were to do that then

all of a sudden this is going to be a

string so it's not considered a number

inside the PHP language anymore it is

actually considered to be a piece of

text just like a string up here and you

can actually tell by the color that it

actually changed it to text now we do

also have something called a float which

is something that we see happen a lot in

many other programming languages which

is essentially when you have a number

that has decimal points so if you were

to write something like

2.5678 then this is going to be

considered a float because it has

decimal points and then we do also have

one more scalar type which is called a

Boolean now I'm just going to write bull

even though it is spelled Boolean we're

just gonna write bull for short and this

one is going to be a true or false

statement so essentially is something

true or is it false and the values for

that is going to be false or it is going

to be true now it is also important to

mention here that if you were to have

numbers in here and you were to run this

as a Boolean then one is also going to

return as true and 0 is going to return

as false but in most cases we do just

use true or false when it comes to this

type of data here and just because I

talked about it in the last video let's

go and create a comment for this section

here so know exactly what this is so

we're going to create a one line comment

and I'm going to call this one scalar

types now the next one we have is

actually one that we're not going to do

too much with here in the beginning but

we do also have a array type so we can

actually go and create a comment and

call this one array type and essentially

a array is when we have a variable that

has multiple pieces of data inside of it

so just like scalar types which means

contains one value in the case of an

array we have multiple values inside one

variable so could for example create a

variable called array and I can name

this one equal to multiple pieces of

data now we do have two different ways

you can create an array one is by

writing array parentheses semicolon and

then you can add multiple pieces of data

in here which could for example be a

bunch of strings so I can go in here and

say we have one string which is called

Daniel and then I can create a comma and

then add a second string which could be

Bella

and then I can add a third piece of data

and I can just keep piling data on

inside this array here so we can say

Theta

which is also a string and then we could

of course rename the array to something

like names if that makes a little bit

more sense to what exactly this piece of

data has inside of it but essentially

this is going to be a bunch of data

inside one variable and just to mention

it since I did mention there was another

way to do this instead of creating array

parentheses you can also do a square

bracket and then close it off using a

square bracket as well just like this

now if you just started following this

course here you should have a newer

version of PHP but if you do run PHP 5.4

or lower then these square brackets are

not going to work when it comes to

writing a PHP code so if you run a older

version of PHP then you do have to do it

the way by creating this array around it

but just like I said if you're a little

bit confused about why we use arrays

inside our code you may have questions

about it don't worry too much about it

because you will get to talk more about

arrays in the future for now like I said

you're only going to have to worry about

these different scalar types here I do

want to mention one more data type

though even though it's not one you

should concern yourself with here at the

beginning since this is something that's

a little bit further ahead in this

course here but we do also have

something called an object type so we

can say object type and an object type

is essentially just when we have a

object that is equal to a variable

objects is something we create based on

classes which is something we again are

not talking about right now but when we

do instantiate a class we do actually

create a variable that is equal to an

object based off of that class so I

could for example say that we have a

variable called object and then we set

it equal to a new object which is going

to be the name of the new object so we

could for example say car parentheses

and semicolon and this would instantiate

a new car object which of course right

now can't find because we don't have it

but once we do have a class called card

that we can instantiate then this is not

going to throw an error message but like

I said we're not really going to worry

too much about arrays and Optics right

now this early on in this course here so

don't worry if you get confused about

them because that is perfectly normal

even though we're not really supposed to

talk about raising Optics yet I still

thought it was important to just kind of

like mention them because it is

something that is very used inside PHP

so knowing about them so you have kind

of like a a little bell inside your head

when we talk about objects in a future

episode and you think to yourself oh

wait I heard about that at some point

inside this course here and then you

might go back to this lesson here and

think oh yeah we talked about objects in

that early lesson oh now we get to talk

about what exactly it is so don't worry

too much about it right now it is

something that you just need to have

kind of like in the back of your head

it's not important right now the only

thing you need to worry about right now

is that we have these scalar types and

when we actually create the variable we

declare the variable and then we

initialize it by assigning a value to it

the reason I mention that is because it

is possible to go down and create a

variable and let's just go and call it

names and not assign anything to it and

when you do this depending on the

context of when you use this variable it

is going to default to a certain value

type so if you were to use this one in a

string context then it will just go and

say oh okay so this is supposed to be a

string automatically and then it's just

going to assign a empty string to it and

it will actually do something that looks

like this so we just have an empty

string that doesn't have any sort of

value inside of it and this is what it's

going to default to and the same thing

goes for integers floats and booleans

and arrays and objects they all default

to something so in this case if I were

to go ahead let's just go and use these

up here so as a default a string

defaults to nothing so just an empty

string with double quote by the way an

integer is going to default to zero and

the same thing goes for floats they also

default to zero and when it comes to

booleans they default to false and just

to mention it here when it comes to an

array so if we were to create a array

because we did talk about them in this

video so we do also need to just kind of

mention this it is going to default to a

empty pair of square brackets and when

it comes to an object

they default to null which means nothing

null is not a concept that we're going

to talk about right now but it just

basically means nothing however when it

comes to declaring a variable you should

always initialize it the reason I say

this is because sometimes when we do

create variables we don't know what

should be inside the variable just quite

yet and in those cases we just declare a

variable but we wait with assigning any

sort of value to it and when those

moments happen you should not do it this

way because you do risk getting error

messages inside your code so make sure

that you always assign something to it

by initializing the variable so with

strings you put empty double quotes with

a integer you put a zero the same thing

with floats if you put a Boolean always

set it to false arrays are just going to

have these square brackets here and

objects are just going to be null so

these are going to be the default values

you should always put inside a variable

if you don't know what kind of data you

should put inside of it just quite yet

otherwise your interpreter is just going

to throw you a warning in a lot of cases

so so just go ahead and make that into a

habit and here at the end before we end

up the episode I just want to say that

it is perfectly normal to be completely

overwhelmed with all this information

here because this is a lot of

information I'm dumping on people

especially if this is your first

programmer language this is going to be

completely new and this is going to be a

lot of information I just want to say

that it's perfectly normal to be

overwhelmed and in the future we will

get to do many more practical examples

so we do actually use variables for

something and we use many different data

types and it is something that is just

going to be a bit more natural when you

actually start seeing how these are used

in Practical examples and when you get

that little oh okay Epiphany moment

where okay so this is how we use these

different things we've learned up until

now then at that point you will remember

things a lot easier okay so don't be

worried about if you can't memorize all

these things because no one expects you

to memorize all these things in one

sitting it is something that sticks with

you as you start practicing PHP along

the way just to give a short example

here at the end just so people know

exactly how we can use variables inside

our code if I were to go back inside my

body sex here and at the very top I'm

going to go ahead and declare a variable

called name I'm going to set this one

equal to a string called Danny Crossing

and what we can do here is we can go

below and create a paragraph inside HTML

then I can just go and say hi

my name is and then we're going to open

up PHP tags close it off again comma and

I'm learning

PHP then what you're going to do is

you're going to go up and grab your

variable name and you're going to go

inside your PHP tags and you're going to

Echo out your variable name semicolon

and when you do this and go inside the

browser and refresh it you can see that

now it says hi my name is Danny Crossing

and I'm learning PHP so in this sort of

way we can take data or variables and we

can use them inside our code or inside

our HTML if you want to do that to

Output data in this sort of sense like

this is a very basic example but just to

kind of show that we can use variables

to reference to data that we assign to

variables and just to mention one more

thing because something we can also do

is we can go down and say I want to

create a new variable and I just go

ahead and call this one something like

test just to give it some kind of name I

can assign equal to name so in this case

here we have a variable that is assigned

equal to a variable and it would take

this name and copy it down instead of

the echo you'll now notice that we still

do get hi my name is Danny Crossing and

I'm learning PHP and that is because

this this first variable here has a

piece of data assigned to it and then

the second variable down here has that

same variable which has data inside of

it assigned to itself so we can also

assign variables equal to variables in

this sort of way here and with that we

now know a lot about variables so I hope

you enjoyed this episode here and I'll

see you in the next video

[Music]

[Music]

thank you