Hello World

In keeping with the programming tradition, here's a simple Hello World program in Java:

public class HelloWorld {

    public static void main(String[] args) {
        System.out.println("Hello World.");
    }
}

And here's the equivalent in Rust:

fn main() {
    println!("Hello World.");
}

A few things to note:

• There's much less ceremony in the Rust version of the program
• In Rust, a function is defined using the fn keyword
• In both cases, we need a main funtion/method as the entry point to our program
• Unlike in Java, Rust's main function isn't contained in a class
• Rust uses the println! macro to print the string to the output (notice the bang !)

In Java's case, it's clear from the method signature that the main method returns nothing (hinted by the use of void as the return type).

Although it's not clear from the function signature, the Rust version also returns nothing. In the absense of an explicit return type, a Rust function returns void, which is represented by ().

This slightly modified Rust version works exactly the same way as the one above:

fn main() -> () {
    println!("Hello World.");
}