Making a "Hello World" program in Rust

The journey to learning any programming language starts with a simple “Hello World” program. To create a “Hello World” program in Rust, follow these steps:

1. Create a source file and name it main.rs – rust files always end with the .rs extension.
2. Open the main.rs file and write the following code in it:

fn main() {
  println!("Hello world!");
} 

3. Save the file and open a terminal window in the directory you are working in.
4. If you are using Linux or MacOS, enter the following commands to execute the program:

$ rustc main.rs
$ ./main

5. If you are using Windows, then the commands to compile and execute the program are:

> rustc main.rs
> .\main.exe

The following is an executable “Hello World” program in Rust​:

Explanation

• The code fn main() {} defines a function named main. The main function is special because it is always the first code that runs in a Rust executable program. Any arguments will go inside the parenthesis () and the code will go inside the curly brackets {}.

• The code println!("Hello, world!"); simply prints the string inside the parenthesis onto the screen. Note that println! has an exclamation mark at the end of it – ​this means that it is a macro and not a function. While functions generate a function call, macros are expanded into a source code that is compiled with the rest of the program.