Hello World

This is the source code of the traditional Hello World program.

1. // This is a comment, and will be ignored by the compiler
2. // You can test this code by clicking the "Run" button over there ->
3. // or if prefer to use your keyboard, you can use the "Ctrl + Enter" shortcut

5. // This code is editable, feel free to hack it!
6. // You can always return to the original code by clicking the "Reset" button ->

8. // This is the main function
9. fn main() {
10. // The statements here will be executed when the compiled binary is called

12. // Print text to the console
13. println!("Hello World!");
14. }

println! is a macro that prints text to the console.

A binary can be generated using the Rust compiler: rustc.

1. $ rustc hello.rs

rustc will produce a hello binary that can be executed.

1. $ ./hello
2. Hello World!

Activity

Click ‘Run’ above to see the expected output. Next, add a new line with a second println! macro so that the output shows:

1. Hello World!
2. I'm a Rustacean!