Rust/C2/Variables-and-Mutability-in-Rust/English - Revision history

Nancyvarkey at 05:48, 21 June 2021

2021-06-21T05:48:28Z

Pravin1389 at 16:53, 1 February 2021

2021-02-01T16:53:26Z

Nancyvarkey at 08:33, 21 January 2021

2021-01-21T08:33:53Z

Kr.jayesh: Created page with "Title of the script: Variables and Mutability Author: Jayesh Katta Ramalingaiah Domain Reviewer: Novice Reviewer: Praveen S Keywords: Rust, cargo, package manager, variab..."

2021-01-14T19:07:45Z

Created page with "Title of the script: Variables and Mutability Author: Jayesh Katta Ramalingaiah Domain Reviewer: Novice Reviewer: Praveen S Keywords: Rust, cargo, package manager, variab..."

New page

Title of the script: Variables and Mutability

Author: Jayesh Katta Ramalingaiah

Domain Reviewer:

Novice Reviewer: Praveen S

Keywords: Rust, cargo, package manager, variables, mut

{| border = “1”
|| <center>'''Visual Cue'''</center>
|| <center>'''Narration'''</center>

|-
|| Slide: Title
|| Welcome to the spoken tutorial on “'''Variables and Mutability in RUST'''”.

|-
|| Slide:

Learning Objectives
|| In this tutorial, we will learn:

* How to create '''variables'''.
* About '''mutability''' and
* How to '''mutate variables''' in '''Rust'''

|-
|| Slide: System Specifications
|| This tutorial is recorded using:

* '''Ubuntu Linux''' OS version 18.04
* '''Rust''' version 1.47.0
* '''Visual Studio Code''' version 1.45.0 ('''code editor''')

However you may use any other '''editor''' of your choice.

|-
|| Slide : Pre-requisites
|| To practice this tutorial,

* You should be familiar with '''compiling''' and '''running Rust''' files'''.'''
* If not, please go through the prerequisite '''Rust''' tutorials on this website.

|-
|| Slide: Code files
||
* The files used in this tutorial are available in the''' Code files''' link on this tutorial page.
* Pls download and extract the file.
* Make a copy and then use it for practising.

|-
|| Slide: Mutability
||
* In '''Rust, variables''' are '''immutable''' by default.
* That means, once the '''variable''' is '''declared''' we cannot change its value.
* This is one of many advantages in '''Rust '''
* That encourages us to write our code in a way that,
* It takes advantage of the safety and concurrency that '''Rust''' offers.

To understand this let us create a '''project''' and see how this works.

|-
|| Press '''Ctrl+Alt+T '''keys
|| Open the '''terminal''' by pressing '''Ctrl,Alt''' and '''T''' keys simultaneously on the keyboard.

Ensure that you have '''root permissions''' to '''run''' the '''commands'''.

|-
|| Only Narration
|| Here onwards, please remember to press the '''Enter''' key after typing each '''command'''.

|-
|| <nowiki>[Terminal] Type:</nowiki>

cd Desktop/MyRustProject

<nowiki>[Enter]</nowiki>
|| Using '''cd''' command go to the '''Rust''' practice folder which we created earlier.

|-
|| <nowiki>[Terminal] Type:</nowiki>

<nowiki>cargo new variables_mutability [Enter]</nowiki>
|| Let us create a new '''project''' named '''new variables_mutability.'''

Type the '''command''' as shown.

|-
|| Open Visual Studio Code editor.
|| You may use any '''editor''' of your choice.

I will use '''Visual Studio Code editor '''for this demonstration'''.'''

|-
|| <nowiki>[Editor] </nowiki>

Welcome Page ->

Open Folder ->

variables_mutability
|| Open the created '''project''' by clicking on the '''Open folder''' link in the '''Welcome page.'''

Browse and locate the folder “'''variables_mutability'''”.

Then click on the '''OK '''button at the top right corner.

|-
|| <nowiki>[Editor] </nowiki>

Click on '''variables_mutability'''
|| Under the '''EXPLORER''' section, expand the '''project''' folder “'''variables_mutability'''” by clicking on it.

|-
|| <nowiki>[Editor] </nowiki>Expand '''src '''and click on '''main.rs'''
|| Then expand '''src''' and open the '''main.rs''' file.

|-
|| <nowiki>[Editor] Type: </nowiki>

fn main(){

let a = 1;

print!(“The value of a is {}”,a);

a=2;

print!(“The value of a is {}”,a);

}
|| In the '''editor''', replace the '''code''' as shown.

|-
|| <nowiki>[Editor] </nowiki>

Highlight: '''let '''
|| '''let keyword''' is used to declare '''variables''' in '''Rust.'''

|-
|| <nowiki>[Editor] Highlight: </nowiki>

'''let a = 1;'''
|| Here we have initialized the '''variable a '''and assigned the value '''1''' to it.

|-
|| <nowiki>[Editor] Highlight:</nowiki>

'''println!("The value of a is {}",a);'''
|| Using the '''println '''macro we are printing the value.

|-
|| <nowiki>[Editor] Highlight:</nowiki>

print!("The value of a is '''{}'''",a);
|| Here the '''{} '''is the '''format specifier.'''

|-
|| <nowiki>[Editor] Highlight:</nowiki>

print!("The value of a is {}",'''a''');
|| In the '''print method''', the '''variable a''' is after the comma.

It is the value for the respective '''format specifier'''.

|-
|| <nowiki>[Editor] Highlight:</nowiki>

'''a = 2;'''
|| Here, we are trying to reassign the '''variable''' to 2.

|-
|| <nowiki>[Editor] Highlight:</nowiki>

'''print!("The value of a is {}",a);'''
|| After reassigning we are printing the '''variable’s''' value to see what does the value contain.

|-
|| Ctrl + S
|| Save the file.

|-
|| Switch to terminal
|| Switch back to the '''terminal.'''

|-
|| <nowiki>[Terminal] Type: </nowiki>

cd '''variables_mutability'''

<nowiki>[Enter]</nowiki>
|| Go to the '''project''' folder '''variables_mutability '''using the '''cd command.'''

|-
|| <nowiki>[Terminal] Type: </nowiki>

'''cargo build '''<nowiki>[Enter]</nowiki>
|| To '''compile '''the '''Cargo project''', type '''cargo build'''

|-
|| <nowiki>[Terminal] Highlight: </nowiki>

'''cannot assign twice to immutable variable ‘a’'''

|| Here, we can see an error - '''cannot assign twice to immutable variable ‘a’.'''

Recall in the beginning of the tutorial I had mentioned that''' variables''' are '''immutable''' by default.

|-
|| Switch to Editor
|| So switch back to the '''editor.'''

|-
|| <nowiki>[Editor] Type:</nowiki>

let''' mut '''a = 1;
|| Now, type '''mut '''in between '''let''' and '''a'''.

|-
|| <nowiki>[Editor] Highlight:</nowiki>

let''' mut '''a = 1;
|| Here we are telling the '''compiler''' that the '''initialized variable''' is '''mutable'''.

|-
|| Ctrl + S
|| Save the file.

|-
|| Switch to terminal
|| Switch back to the '''terminal.'''

|-
|| <nowiki>[Terminal] Type: </nowiki>

<nowiki>cargo run [Enter]</nowiki>
|| Now type '''cargo run'''

|-
|| <nowiki>[Terminal] Highlight</nowiki>

The value of a is 1The value of a is 2
|| We can see the output.

Both the '''initialized''' and the modified values are printed successfully.

|-
|| <nowiki>[Terminal] Highlight: </nowiki>

cargo run
|| After switching back I directly did a '''cargo run''' without '''compiling''' the '''project''' again.

Did you notice that?

When we do a''' cargo run''' the '''package manager''' will '''build''' again and '''run''' the '''project'''.

So going forward, we can directly use '''cargo run''' to '''build '''and '''run '''the '''project''' in one go.

|-
|| Only narration
|| With this we have come to the end of this tutorial.

let’s summarize.

|-
|| Slide''': '''Summary''' '''
|| In this tutorial, we have learnt:

* How to create '''variables'''
* About '''mutability''' and
* How to '''mutate variables'''

|-
|| Slide: Assignment
|| As an assignment,

* Go to the project folder '''rust-assignment'''
* In the '''main.rs''' file
** Create a '''variable '''named '''s''' and make it '''mutable'''.
** Assign '''13''' as a value to '''s'''
** Print the value of '''s'''
** Reassign the value of '''s''' as '''19'''
** Print the value of '''s'''
* '''Compile '''and '''execute '''the project.
* Observe the output in the '''Terminal'''

|-
|| '''Slide: '''About Spoken Tutorial Project
||
* The video at the following link summarises the Spoken Tutorial project.
* Please download and watch it

|-
|| '''Slide:''' Spoken tutorial workshops
||
* We conduct workshops using spoken tutorials and give certificates.
* For more details, please write to us.

|-
|| Slide: Forum questions
|| Pls post your timed queries in this forum

|-
|| Slide: Acknowledgement
|| Spoken Tutorial Project is funded by Ministry of Education, Government of India

|-
|| Slide: Thanks
|| This is Jayesh signing off. Thank you for joining

|}

@@ Line 3: / Line 3: @@
 Author: Jayesh Katta Ramalingaiah
-Domain Reviewer:
+Domain Reviewer: Vigneshwer Dhinakaran
-Novice Reviewer: Praveen S
+Novice Reviewer: Praveen S.
 Keywords: Rust, cargo, package manager, variables, mut

@@ Line 49: / Line 49: @@
 || Slide: Code files
 ||
-* The files used in this tutorial are available in the''' Code files''' link on this tutorial page.
+* The file used in this tutorial is available in the''' Code files''' link on this tutorial page.
 * Pls download and extract the file.
 * Make a copy and then use it for practising.

@@ Line 28: / Line 28: @@
 * About '''mutability''' and
 * How to '''mutate variables''' in '''Rust'''
 |-
@@ Line 47: / Line 45: @@
 * You should be familiar with '''compiling''' and '''running Rust''' files'''.'''
 * If not, please go through the prerequisite '''Rust''' tutorials on this website.
 |-
@@ Line 56: / Line 52: @@
 * Pls download and extract the file.
 * Make a copy and then use it for practising.
 |-
@@ Line 99: / Line 93: @@
 Type the '''command''' as shown.
 |-
@@ Line 122: / Line 113: @@
-Browse and locate the folder “'''variables_mutability'''”.
+Browse and locate the  “'''variables_mutability'''” folder.
@@ Line 131: / Line 122: @@
 Click on '''variables_mutability'''
-|| Under the '''EXPLORER''' section, expand the '''project''' folder “'''variables_mutability'''” by clicking on it.
+|| Under '''EXPLORER''' section, expand the '''project  “variables_mutability'''” by clicking on it.
 |-
 || <nowiki>[Editor] </nowiki>Expand '''src '''and click on '''main.rs'''
-|| Then expand '''src''' and open the '''main.rs''' file.
+|| Then expand the '''src''' and open the '''main.rs''' file.
 |-
@@ Line 158: / Line 149: @@
 Highlight: '''let '''
-|| '''let keyword''' is used to declare '''variables''' in '''Rust.'''
+|| '''let keyword''' is used to '''declare variables''' in '''Rust.'''
 |-
@@ Line 165: / Line 156: @@
 '''let a = 1;'''
-|| Here we have initialized the '''variable a '''and assigned the value '''1''' to it.
+|| Here we have '''initialized''' the '''variable a '''and assigned the value '''1''' to it.
 |-
@@ Line 172: / Line 163: @@
 '''println!("The value of a is {}",a);'''
-|| Using the '''println '''macro we are printing the value.
+|| Using the '''println macro''' we are printing the value.
 |-
@@ Line 179: / Line 170: @@
 print!("The value of a is '''{}'''",a);
-|| Here the '''{} '''is the '''format specifier.'''
+|| Here the '''{} open and close brace'''is a '''format specifier.'''
 |-
@@ Line 186: / Line 177: @@
 print!("The value of a is {}",'''a''');
-|| In the '''print method''', the '''variable a''' is after the comma.
+|| In the '''print method''', the '''variable a''' is after comma.
@@ Line 227: / Line 218: @@
 '''cargo build '''<nowiki>[Enter]</nowiki>
-|| To '''compile '''the '''Cargo project''', type '''cargo build'''
+|| To '''compile '''the '''Cargo project''', type '''cargo build'''.
 |-
@@ Line 234: / Line 225: @@
 '''cannot assign twice to immutable variable ‘a’'''
 || Here, we can see an error - '''cannot assign twice to immutable variable ‘a’.'''
@@ Line 250: / Line 238: @@
 let''' mut '''a = 1;
-|| Now, type '''mut '''in between '''let''' and '''a'''.
+|| Now, type '''m u t '''in between '''let''' and '''a'''.
-−
-−
@@ Line 291: / Line 277: @@
 cargo run
-|| After switching back I directly did a '''cargo run''' without '''compiling''' the '''project''' again.
+|| After switching back, I directly did a '''cargo run''' without '''compiling''' the '''project''' again.
@@ Line 307: / Line 293: @@
-let’s summarize.
+Let’s summarize.
 |-
 || Slide''': '''Summary''' '''
 || In this tutorial, we have learnt:
 * How to create '''variables'''
 * About '''mutability''' and
 * How to '''mutate variables'''
 |-
@@ Line 324: / Line 307: @@
 || As an assignment,
-* Go to the project folder '''rust-assignment'''
+* Go to the '''project''' folder '''rust-assignment'''
 * In the '''main.rs''' file
 ** Create a '''variable '''named '''s''' and make it '''mutable'''.
@@ Line 331: / Line 314: @@
 ** Reassign the value of '''s''' as '''19'''
 ** Print the value of '''s'''
-* '''Compile '''and '''execute '''the project.
+* '''Compile '''and '''execute '''the '''project'''.
 * Observe the output in the '''Terminal'''
 |-
@@ Line 341: / Line 322: @@
 * The video at the following link summarises the Spoken Tutorial project.
 * Please download and watch it
 |-
@@ Line 349: / Line 328: @@
 * We conduct workshops using spoken tutorials and give certificates.
 * For more details, please write to us.
 |-