Variable Basics (Updated) | Godot GDScript Tutorial | Ep 1.1

Summary

This video script offers an insightful look into the concept of variables in computer programming, particularly within the context of Gdscript. It explains that a variable is essentially a container for values and demonstrates how to create and assign values to them, emphasizing the importance of unique naming to avoid errors. The script delves into type variables, showcasing the use of data types to restrict variable content and the casting operator for value conversion. It also touches on common data types and the use of variables when data changes over time, providing practical examples to illustrate the concepts.

Takeaways

• 📚 A variable in programming is a storage address with a symbolic name that holds a value, essentially a container for data.
• 🔑 In GDScript, variables are declared with the keyword 'var' followed by a unique name to ensure no name conflicts in the script.
• 🟡 Parentheses in variable declarations are optional in GDScript, allowing for the creation of empty variables or variables with assigned values.
• 🔄 The assignment operator (=) is used to assign a literal value or data object to a variable in GDScript.
• 🚫 Variables must have unique names; otherwise, an error is thrown in GDScript.
• 🔠 Typed variables are declared with a colon (:) followed by the desired data type, which restricts the variable to that type only.
• 🛑 Assigning a value of a different type than declared will result in an error in GDScript, enforcing type consistency.
• 🔄 The casting operator can be used to convert values to a specific type, such as converting an integer to a string or vice versa.
• 🔢 Common data types in GDScript include integers, booleans, strings, and floats, which can be explicitly declared or inferred from assigned values.
• 📐 GDScript also supports casting to object types that are subclasses of another, such as assigning a Sprite to a variable declared as Node2D.
• 💡 Variables are essential when data needs to change over time, like the health of a player in a game, demonstrating the dynamic nature of variables.

Q & A

What is the dictionary definition of a variable in computer programming?

A variable, also known as a scalar, is a storage address paired with an associated symbolic name that contains a known or unknown quantity of information, often referred to as a value. In simpler terms, it's a container that holds a value.

How is a variable created in Gdscript?

In Gdscript, a variable is created by typing the keyword 'var' followed by a unique name. This name must be unique within the script to avoid conflicts.

What is the significance of using unique names for variables in Gdscript?

Unique names are important to ensure that each variable is distinct and to prevent any conflicts or errors that may occur if two variables share the same name.

What is the purpose of the assignment operator in variable declaration?

The assignment operator, represented by the equals sign, is used to assign a literal value or data object to a variable during its declaration.

What happens if a variable in Gdscript is not assigned a value?

If a variable is not assigned a value, it will contain the data type 'null' by default, indicating that it has no value.

What is a typed variable and how is it declared in Gdscript?

A typed variable is a variable that has an explicitly declared data type. It is declared by adding a colon followed by the desired data type after the variable name.

Why is declaring data types on variables considered good practice in Gdscript?

Declaring data types on variables is good practice as it reduces confusion about the purpose of the variable and ensures that only compatible types are assigned to it, thus preventing type-related errors.

What is the effect of assigning a value of a different type to a typed variable in Gdscript?

Assigning a value of a different type to a typed variable will result in an error because Gdscript expects the variable to hold values of the declared type only.

How can you convert a value to a specific data type in Gdscript?

You can convert a value to a specific data type using the casting operator, which allows you to assign a value of one type to a variable of another type, effectively changing the value's type.

What are some common data types you might use with typed variables in Gdscript?

Some common data types in Gdscript include integers, booleans, strings, and floats.

How can you infer the data type of a variable based on the assigned value?

You can infer the data type of a variable by assigning a literal value to it without explicitly declaring the type. Gdscript will automatically recognize the type of the value and apply it to the variable.

Can Gdscript handle objects and class casting?

Yes, Gdscript can handle objects and class casting, allowing you to assign values of subclasses to variables of superclass types, provided the assignment is compatible.

When should you use variables in a Gdscript program?

Variables should be used when you have data that needs to change over the lifetime of the game or program, such as a player's health that may vary during gameplay.

Outlines

00:00

📚 Understanding Variables in Computer Programming

This paragraph introduces the concept of a variable in computer programming, equating it to a container that holds a value. It explains the process of creating a variable in GDScript using the 'var' keyword followed by a unique name. The importance of variable names being unique is emphasized, and the use of parentheses for optional value assignments is discussed. Examples are provided to illustrate how to create variables with and without initial values, and the concept of type variables is introduced, which involves explicitly declaring a data type for the variable. The paragraph also covers the use of the casting operator to convert data types and mentions common data types such as integers, booleans, strings, and floats. It concludes with a brief mention of object assignment and class casting in GDScript.

05:00

🔑 Advanced Variable Declaration and Use Cases

The second paragraph delves into more advanced aspects of variable declaration in GDScript, including the mandatory and optional components of variable syntax. It outlines the steps for declaring variables, typed variables, and assigning values, using the assignment operator. The paragraph also touches on the ability of GDScript to cast classes, providing an example of assigning a Sprite class value to a variable of type Node2D. The importance of using variables when data needs to change over time is highlighted, with 'Player Health' serving as an example of a variable that may change during the game's lifecycle. The summary ends with a note on the practical use of variables and a sign-off for the episode.

Keywords

💡Variable

In computer programming, a 'variable' is a fundamental concept that refers to a storage location paired with a symbolic name, which holds a value that can change over time. In the context of the video, variables are likened to containers that store data, such as a player's health in a game. The script discusses how to create and assign values to variables in GDScript, emphasizing their importance in programming for dynamic data storage.

💡Scalar

A 'scalar' is a term used to describe a simple value in programming, as opposed to a more complex data structure. Although the term is not explicitly defined in the script, it is implied when describing a variable as a storage address paired with a symbolic name that contains a quantity of information. The script uses 'scalar' to highlight that variables can hold single values, such as integers or strings.

💡GDScript

GDScript is a scripting language used in the Godot game engine. It is designed to be simple and easy to learn, making it ideal for game development. The video script focuses on GDScript's syntax and conventions for creating and using variables, such as the use of the 'var' keyword and the assignment operator for initializing variables.

💡Unique Name

In programming, each variable must have a 'unique name' to distinguish it from other variables. The script emphasizes the importance of naming variables uniquely to avoid conflicts within the script. For instance, trying to use the same name for multiple variables will result in an error in GDScript.

💡Assignment Operator

The 'assignment operator', represented by the equals sign (=), is used to assign a value to a variable. The script provides examples of how to use the assignment operator to initialize variables with literal values, such as assigning the integer value 100 to a variable named 'Player Health'.

💡Data Type

A 'data type' defines the kind of data a variable can hold, such as integers, strings, or booleans. The script explains how to declare a variable's data type in GDScript using a colon followed by the type, which helps in ensuring that the variable only contains values of the specified type. For example, a variable declared as 'int' can only hold integer values.

💡Type Casting

Type casting is the process of converting a value from one data type to another. The script demonstrates how to use the casting operator in GDScript to assign values of one type to a variable that expects another type, such as converting an integer to a string or vice versa.

💡Literal Value

A 'literal value' is a specific value that is directly embedded in the code, such as the number 10 or the string 'hello'. The script shows how to assign literal values to variables using the assignment operator, and how these values can be inferred to set the data type of the variable.

💡Boolean

A 'boolean' is a data type that can only hold two values: true or false. In the script, booleans are mentioned as one of the common data types used in variables, and an example is given where the boolean value 'true' is assigned to a variable named 'a boolean'.

💡Float

A 'float' is a data type used to represent real numbers with a fractional part. The script discusses how to declare a variable with a float data type and assign it a value, either directly as a floating-point number or by converting an integer to a float.

💡Class Casting

Class casting in GDScript refers to the process of assigning an object of a subclass to a variable of a superclass type. The script briefly touches on this advanced topic, showing an example where a 'Sprite' object, which is a subclass of 'Node2D', is cast to a 'Node2D' type.

Highlights

A variable in computer programming is defined as a storage address paired with a symbolic name containing a value.

In layman's terms, a variable is a container that holds a value.

In GDScript, variables are created using the keyword 'var' followed by a unique name.

Variable names must be unique within a script to avoid errors.

Optional parentheses can be used to assign a value or leave a variable empty.

The assignment operator, represented by the equals sign, is used to assign values to variables.

An example of creating a 'Player Health' variable with an initial value of 100.

Variables can be created without an initial value, defaulting to the data type 'null'.

Type variables allow for explicit data type declaration using a colon and the desired data type.

Declaring data types reduces confusion and enforces the intended use of a variable.

Attempting to assign a value of the wrong type to a type variable will result in an error.

Casting operators can be used to convert values to specific data types, such as converting an integer to a string.

Common data types in GDScript include integers, booleans, strings, and floats.

Data types can be inferred from the value assigned to a variable.

GDScript supports casting of classes, allowing assignment of subtype objects to variables with a superclass data type.

Variables should be used when data needs to change over the lifetime of a game or program.

The format for declaring variables in GDScript includes the 'var' keyword, a unique name, optional typing, and assignment with '='.

Variables are essential for managing data that changes dynamically within a program.

Transcripts

Let's take a look at the dictionary definition of a

variable in computer programming,

a variable also called a scalar is a storage address paired

with an associated symbolic name, which contains a

known or unknown quantity of information often referred to

as a value.

In layman's term, a variable is a container that

contains a value.

Now, how exactly do we go about creating a variable?

Well, in Gdscript to write a variable, you type out the

key word of var spelled V a R followed by a unique name.

This is important because a variable cannot have a name

that already exists in your script.

Now to write a variable, you simply write out the key

word var spelled V A R followed by your unique name and

everything in yellow is mandatory.

However, everything in the parentheses

is completely optional.

This means you can create a variable that is empty or you

can assign your variable a literary value or data object

using the assignment operator, which is represented by the

equals sign symbol.

Now let's go ahead and take a look at two examples.

In the first example, you can see here we've created a

variable called Player Health and we've assigned it with

the assignment operator.

The literal value in this case, the literal integer

value of one hundred.

You can also create the same variable without

assigning a value.

In this case, we've created a variable called player health

and we have not assigned it any value.

As a matter of fact, if we do not assign a value to

our variables, they will contain the data type

no by default.

And again, variables must have unique names or an error is

thrown in gdscript.

You can also use something called type two variables.

A type variable is just a data type that is explicitly

declared on your variable by adding the colon symbol,

followed by the data type in which you wish to

limit your variable.

In this case, the first example is a variable called LifePoint

and using the colon sine symbol followed by the int key word.

What we're saying is that our variable, called life

points can only have integer values assigned to it.

Declaring data types on variables is usually considered

good practice as it leaves less room for confusion on the

purpose of the specific variable.

Assigning a value that is not the declared type will

throw an error.

Let's go ahead and take a quick look.

In this case, we have a variable called text and we've

explicitly assigned it a data type of string and we are

trying to assign it a literal integer value of ten.

This line of code will not work because it will in fact throw

an error because Gdscript is expecting a string data type to

be assigned to our variable called text in gdscript values

assigned to a type variable must have a compatible type if

you need to coerce a value to be a certain type.

Use the casting operator as in the first example, you can see

we have a variable called text with a declared data type of

string and we are assigning it the value ten as a string.

What this will do is convert the integer value ten into a

string value ten.

The second example, we have a variable called a NUM and we

assign it a string value ten as an integer.

What this does is it converts our string value of ten into an

integer value of ten.

Lastly, we have a variable called NUM float with the

declared data type of float and we assign it the value of the

integer value ten as a float.

And again, this will convert our integer value of ten into a

float which will then be assigned to our variable called

num float common data types you may find yourself using

with your type.

The variables include integers, booleans,

strings and bloats.

Instead of typing them out, you can also infer the data

type onto your variable by the value or literal value you are

assigning into that variable.

For example, we have a variable called a number and we are

assigning and inferring both the integer value and the

integer data type onto the variable called a number.

The same thing is true for the variable called a boolean.

We.

Are inferring and assigning the boolean value true and the data

type of bullion onto our variable called a bullion,

and the same thing is true for our variable, a string which is

being inferred and assign the string data type and value.

Hi, friend.

And lastly, are variable of float is being inferred and

assign the negative float value of twelve point

zero in Gdscript.

You may also assign an object that is the subtype of

the CAS type.

Now this is an advanced topic as we have not, nor will we be

going over Godot specific classes.

If you want to learn Godot specific classes, please feel

free to view my Godot basics tutorial series.

Regardless, just for your information, Gdscript does

have the ability of casting classes.

So in this case you can see here we have a variable called

my underscore node2D with the data type of node2D, which is a

Godot specific class and we are assigning it some type of

Sprite class value and we are casting it as a node2D.

Just so you know, the Sprite class is a subclass of the

node2D class and again a more advanced topic.

However, we will be going over classes in a later episode.

Now that we have gone over different ways of declaring

our variables, I have laid out the actual format for declaring

variables in gdscript.

Again, the mandatory pieces of a variable is the key word of

var followed by your unique name.

You can choose to opt it as a typed variable using the colon

symbol followed by your data type, and you also have

the option of assigning it a value.

However, if you choose to assign it a value, you must use

the assignment operator, which is the equal sign symbol

followed by your literal or data object.

And of course you can combine these two by using

the semicolon, followed by the assignment operator,

followed by your literal value, assigning both

the value and its data type to your variable or in this case,

your type variable.

Let's quickly go over when you need to use variables,

you should use variables when you have data that needs to

change over the lifetime of the game or program.

In this example, we have a variable called Player Health

with an assigned literal integer value of one hundred

and the value of the player's health may in fact

change over time.

As you notice, the player health value is not

a constant.

That's all I have for you in this episode.

Thank you so much for joining me and I look forward to seeing

you in the next episode.

I have an amazing day.