Difference between revisions of "Rust/C2/Functions-and-Returning-value-from-function-using-Rust/English"

Learning Objectives

• Create a function
• Create a parameterized function
• Return a value from a function

• 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.

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

• 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.

• Function is a block of organised code, used to perform a single related action.
• Functions provide better modularity for our application and
• High degree of code reusability

Ensure that you have root permissions to run the commands.

cd Desktop/MyRustProject

[Enter]

cargo new functions [Enter]

Type the command as shown.

Welcome Page ->

Open Folder ->

functions

Browse and locate the folder “functions”.

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

Click on functions

fn main(){

display();

}

fn display(){

println!(“Spoken Tutorial”);

}

fn display()

println!(“Spoken Tutorial”);

display();

So, the display function is being called here.

cd functions

[Enter]

Navigate inside the Cargo project functions using the cd command.

cargo run [Enter]

Spoken Tutorial

Now let us learn about parameterized function.

fn main(){

display(1);

}

fn display(a:i32){

println!(“I’m getting {} from main function.”, a);

}

fn display(a:i32)

println!(“I’m getting {} from the main function.”, a);

display(1);

cargo run [Enter]

I’m getting 1 from the main function.

Next let us learn about returning a value from a function.

fn main(){

println!(“The result is {}”,sum(1,2));

}

fn sum(a:i32, b:i32) -> i32{

a+b

}

fn sum(a:i32, b:i32) -> i32

The function should return the added value.

So, we are mentioning the type of value which would be returned after the arrow.

a+b

sum(1,2));

println!(“The result is {}”,sum(1,2));

}

The returned value would be replaced by the format specifier.

cargo run [Enter]

The result is 3

fn sum(a:i32, b:i32) -> i32{

a+b;

}

cargo run [Enter]

Consider removing this semicolon

This is because it is being considered as a statement and not as a return value.

In order to return the value directly without using the return keyword we need to remove the semicolon.

fn sum(a:i32, b:i32) -> i32{

let z = a + b;

z*10

}

let z = a + b;

z*10

Notice that there is no semicolon.

So the value will be returned correctly.

cargo run [Enter]

The result is 30

let z = a + b;

z*10

This is because we have a statement and value being returned.

fn sum(a:i32, b:i32) -> i32{

let z = a + b;

return z*10;

}

Add a return keyword before z*10 and add a semicolon after z*10

cargo run [Enter]

The result is 30

So we have learnt to make the code readable.

We also learnt different ways to return a value from a function.

Let’s summarize.

• Create a function
• Create a parameterized function
• Return a value from a function

• Go to the project folder rust-assignment
• In the main.rs file
  • Create a function that accepts a number as a parameter
  • Print EVEN if the number is even
  • Else print ODD
• Compile and execute the project.
• Observe the output in the Terminal

• The video at the following link summarises the Spoken Tutorial project.
• Please download and watch it

• We conduct workshops using spoken tutorials and give certificates.
• For more details, please write to us.