Working Code
Try running this code in the Rust Playground!
fn main() {
println!("Hello, DaleSchool!");
println!("Welcome to the world of Rust 🎉");
}
Try It Yourself
Change the text inside println! to your own name. What happens?
"Why?" — What Kind of Language Is Rust?
Rust is a fast and safe programming language. Every Rust program starts inside fn main(). For now, just remember that you write your code inside this block.
println! is a command that prints text to the screen. You'll notice the ! at the end — we'll get to that later.
Deep Dive
What's the exclamation mark in println! for?
In Rust, anything with a ! at the end of its name is a macro. It's a bit different from a regular function, but for now you can think of it as a "special function." We'll cover macros in detail later on.
What happens if you leave out the ! after println?
fn main() {
println("Oops, forgot the bang!");
}
The compiler shows an error like this:
error[E0423]: expected function, found macro `println`
Add the ! back and it works again. Don't be afraid of compiler errors — the error messages tell you how to fix things!
- Write a program that prints a 3-line self-introduction using
println!. - What does an empty
println!()produce? Try running it and find out.
Q1. What is the entry point of a Rust program?
- A)
start() - B)
run() - C)
fn main() - D)
begin()