| ## Comments |
| |
| All programmers strive to make their code easy to understand, but sometimes |
| extra explanation is warranted. In these cases, programmers leave _comments_ in |
| their source code that the compiler will ignore but people reading the source |
| code may find useful. |
| |
| Here’s a simple comment: |
| |
| ```rust |
| // hello, world |
| ``` |
| |
| In Rust, the idiomatic comment style starts a comment with two slashes, and the |
| comment continues until the end of the line. For comments that extend beyond a |
| single line, you’ll need to include `//` on each line, like this: |
| |
| ```rust |
| // So we’re doing something complicated here, long enough that we need |
| // multiple lines of comments to do it! Whew! Hopefully, this comment will |
| // explain what’s going on. |
| ``` |
| |
| Comments can also be placed at the end of lines containing code: |
| |
| <span class="filename">Filename: src/main.rs</span> |
| |
| ```rust |
| {{#rustdoc_include ../listings/ch03-common-programming-concepts/no-listing-24-comments-end-of-line/src/main.rs}} |
| ``` |
| |
| But you’ll more often see them used in this format, with the comment on a |
| separate line above the code it’s annotating: |
| |
| <span class="filename">Filename: src/main.rs</span> |
| |
| ```rust |
| {{#rustdoc_include ../listings/ch03-common-programming-concepts/no-listing-25-comments-above-line/src/main.rs}} |
| ``` |
| |
| Rust also has another kind of comment, documentation comments, which we’ll |
| discuss in the [“Publishing a Crate to Crates.io”][publishing]<!-- ignore --> |
| section of Chapter 14. |
| |
| [publishing]: ch14-02-publishing-to-crates-io.html |
