Comments in Rust Programming

Rust Programming

Comments are a way to improve the readability of a program. Comments can be used to include additional information about a program like author of the code, hints about a function/ construct, etc. The compiler ignores comments.

Rust supports the following types of comments: 

• Single-line comments ( // ) : Any text between a // and the end of a line is treated as a comment
• Multi-line (Block) comments (/* */) : These comments may span multiple lines.

Single Line Comments

In Rust, we use two forward slashes // to create a line comment. For example,

Input Example 1

fn main () {

    // declare a variable

    let x = 1;

    println!("x = {}", x);

}{codeBox}

Input Example 2

fn main() {

    let x = 1; // declare a variable

    println!("x = {}", x);

}{codeBox}

Output

x = 1{codeBox}

The comment extends up to the end of the line and is also known as single-line comments.

Multi line (Block) Comments

The symbol /*...*/ to denote the block comment. It starts with /* and ends with */. For example

Input

fn main() {

    /*

    declare a variable

    and assign value to it

    */

    let x = 1;

    println!("x = {}", x);

}{codeBox}

Output

x = 1{codeBox}

You can see the block comment extends for multiple lines.

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