hello world
Hello, world
有多少种 Hello world 的写法？
前置知识：无
练习地址：https://play.rust-lang.org
fn main() {
println!("Hello, world!");
println!("{}", "Hello, world!");
let name = "world";
println!("Hello, {}!", name);
println!("{}", format!("Hello, {}!", name));
let word1 = "Hello";
let word2 = "world";
let word3 = word1.to_owned() + ", " + word2 + "!";
println!("{}", word3);
}