what are comments in Rust language? How do you write a comment in Rust?

Comments are description text about a line or block of a code.

Generally, Comments are for programmers not for Rust interpreters. At runtime, These are ignored by Rust.

In Rust, You can write a comment in different following ways

  • Single-line comments
  • Multi-Line comments
  • Documentation commands

It is always good to practice to add Comments to the below blocks or lines of code

  • Classes description
  • before the method declaration
  • Any complex logic code
  • documentation comments

Single Line comments in Rust

These are also called inline comments.

  • It always starts with double slashes (// ) symbol characters and ends with a line break.
  • There is a space after a pound symbol
  • a string of text that begins with a # symbol is ignored by the Rust compiler.
  • It is a description or piece of text for a single line of code.
  • These comments are not required at the starts in beginning of the line, but also can be written in the middle or end of the line Syntax:
// This is single line comments in the Rust file



// Hello World application
fn main() {
    println!("Hello World app");

Learned single-line comments, How do you write multi-line comments

Multi-line comments

These comments are written in multiple lines and are also called block comments. Hello World program is the first step to learning any programming language Steps to write a Hello World First program code.

Here is a way we can write a multi-line comment with the #\ symbol. Each line starts with a #\ character.

// multi-line comments 1
// multi-line comments 2
// multi-line comments 3

Rust provides special syntax to write a block level comments

// This comment is a multi-line comment 1
// This comment is a multi-line comment 2
// This comment is a multi-line comment 3

This allows you to write multiple lines of code and is ignored by the compiler.

  • Each line starts with a backslash(//) in multiple lines

Block level comments in Rust Example:

// Hello world sample program
// Basic program to print hello world to the console
// First code to write in Rust programming language
fn main() {
    println!("Hello World app");


You learned different types of comments in Rust.

  • single line comments (//)
  • Multiple line comments (Each line begins with //)