All You Need to Know Comments in Rust

In any programming language, Comments are lines of text used to describe information in code. Let’s take one example.

// entry point
fn main() {
    // printing text on the screen
    println!("TechAlgoSpotlight!");
}

Here // entry point and // printing text on the screen are the comments.

While the code is executing, comments are completely ignored by the compiler or interpreter. So, comments are ideally for reading purposes only.

Types of Comments in Rust

There are two main types of comments available in Rust.

• // – Line Comment
• /*…*/ – Blocked Comment

Line Comments in Rust

For Line comments, we have two used two forward slashes like this //.

fn main () {
    // declare your variable name here.
    let x = 10;
    println!("x = {}", x);
}

Output

x = 10

Here, // declare your variable name here. is a line comment, Also known as a single-line comment.

Block Comments in Rust

For Block comments, we used symbols like /*....*/. to denote the comments. It starts with /* and ends with */ symbols.

fn main() {
    /*
    declare a variable
    and assign value here
    */
    let x = 10;
    println!("x = {}", x);
}

Output

x = 10

Here,

/*
declare a variable
and assign value here
*/

is a block comment, You can see block comments using multiple lines and we can write a complete brief in these comments. Hence, it is known as a block comment.

We can also create multiple lines of comments by just using line comments. Here is a small example.

fn main() {
    // declare a variable
    // assign value here
    let x = 10;
    println!("x = {}", x);
}

Note: In the Rust ecosystem, line comments are preferred over block comments.

We can also disable part of the code using line or block comments.

fn main() {
    // declare a variable
    // assign value here
    // let x = 10;
    println!("x = {}", x);
}

In the above code, we just commented variable x. So that println! couldn’t get the value of X.

Instead of printing X in the program will give you an error.

So, this is all we need to know about comments in Rust. Will see more articles about Rust in upcoming articles.