title: How do I tell Cargo to build files other than main.rs?
body: <p>Here is my directory structure:</p>
  
  <pre><code>lowks@lowkster ~/src/rustlang/gettingrusty $ tree .
  .
  ├── Cargo.lock
  ├── Cargo.toml
  ├── foo.txt
  ├── src
  │   ├── boolean_example.rs
  │   ├── function_goodbye_world.rs
  │   ├── listdir.rs
  │   ├── looping.rs
  │   ├── main.rs
  │   ├── pattern_match.rs
  │   └── write_to_file.rs
  └── target
      ├── build
      ├── deps
      ├── examples
      ├── gettingrusty
      └── native
  
  6 directories, 11 files
  </code></pre>
  
  <p>When I run 'cargo build', it seems to only build <code>main.rs</code>. How should I change Cargo.toml to build the rest of the files too?</p>