Rust Tutorial

Rust - Comments



The Comments are added in programming code with the purpose of making the code easier to understand. It makes the code more readable and hence easier to update the code later. Comments are ignored by the compiler while running the code. In Rust, there are two ways of putting a comment.

  • Single line comment
  • Block comment

Single line Comment

It starts with // and ends with the end of that line. Anything after // to the end of the line is a single line comment and will be ignored by the compiler.

Syntax

//single line comment.
statements; //single line comment.

Example:

The example below illustrates how to use single line comments in a Rust code. The compiler ignores the comments while compiling the code.

fn main() {
  // first line comment
  println!("Hello World!"); // second line comment
}

The output of the above code will be:

Hello World!

Block Comment

It starts with /* and ends with */. Anything between /* and */ is a block comment and will be ignored by compiler.

Syntax

/*block 
comment.*/
statements; /*block comment.*/ statements;

Example:

The example below describes how to use multiple line comments in a Rust code which is ignored by the compiler while compiling the code.

fn main() {
/*first 
block comment. */

  println!(/*second block comment.*/"Hello World!");

/*third block comment. */ 
}

The output of the above code will be:

Hello World!

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