Rust-Programming-Language/C2/Functions/English

Visual Cue	Narration
Slide 1	Welcome to the Spoken Tutorial on Functions in Rust.
Slide 2 Learning Objectives	In this tutorial, we will learn about Functions
Slide 3 System Requirements	This tutorial is recorded using Ubuntu Linux OS version 22.04 Rust 1.80.0 Visual Studio Code 1.19.0
Slide 4 Prerequisites	You should be familiar with compiling and running a Rust program
Slide 5 Code File	The following code files is required to practise this tutorial This file is provided in the code files link of this tutorial page
Slide 6 Functions	We will see about functions in Rust. It is a set of statements to perform a specific task Functions organize the program into logical blocks of code.
Slide 7 Functions Functions make the code reusable. It structures your programs and makes them more readable and maintainable.
Slide 8 Function - Example // define a function fn greet() { println!("Hello, World!"); } fn main() { //function call greet(); }	Here, we have created a greet() function that prints "Hello, World!" . To invoke the created function, we need to make a function call. Notice that we are calling the function from inside main(). In Rust, main() is also a function known as a built-in function that has a special meaning.
Open Visual code editor	Let us open the Visual code editor.
	In the menu bar, click on terminal and select New Terminal We can see a terminal window at the bottom.
> cd MyRustProject > cargo new functions	Let us go to our working directory MyRustProject as explained earlier. Type the command cargo new functions and press Enter Open the created project as shown.
	In the main.rs file, copy and paste the code from the Code file.
// define an add function that takes in two parameters fn add(a: i32, b: i32) { let sum = a + b; println!("Sum of a and b = {}", sum); } fn main() { // call add function with arguments add(12, 10); }	In this example, the add function takes 2 parameters and gives the sum as output. Here, a and b are function parameters. i32 is the data type of parameters. 12 and 10 are known as function arguments that are passed to the add function. That means 12 is assigned to a and 10 is assigned to b. Save the file.
Click on Terminal and select New Terminal.	In the menu bar, click on Terminal and select New Terminal.
Type cargo run	In the terminal, type cargo run and see the output. It prints the sum of a and b as 22.
	Next we will see an example for a function with return value. Replace the code as shown.
fn area(length: i32, breadth: i32) -> i32 {    length * breadth } fn main() { let k = area(5, 6); println!("Area of the rectangle = {k}"); } Change the program to return length*breadth	In this example, we define a function to calculate the area of a rectangle. The area function takes two parameters, length and breadth, both of type i32. -> i32 right arrow i32 before the opening curly bracket indicates the function's return type. It returns an i32 value representing the area of the rectangle. In the next line, notice the lack of a semicolon after length * breadth. In Rust, the absence of a semicolon signifies that this line is an expression. The result value is returned by the function. Save the file and run the program. We can see the output as the area of the rectangle is 30. Now let us add a semicolon at the end of length into Breadth statement. Save the file.
	Let us run the program and see how the program works.
Show the error.	It would not return a value and cause a compilation error. This time we get an error, remove this semicolon to return this value. This is because it is being considered as a statement and not as a return value. You can use either conventions  length* breadth without semicolon or return length * breadth with semicolon for returning the value. Save the file and run the program We can observe that the area of the rectangle is 30.
Slide 11 Summary In this tutorial, we learn about Functions	This brings us to the end of this tutorial. Let us summarize.
Slide 12 Assignment	As an Assignment, do the following: 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
Slide 18 Thank You	Thank you for joining.

Contributors and Content Editors

Madhurig, Nirmala Venkat