How to: fmt.Println in Rust

Outputting to your shell or terminal to inform the user of the outcome of a program or valuable debugging information is an essential of every programming language.

GOlang

In Golang you can output text and variables to the terminal via various methods, but fmt is a commonly used one.

package main

import "fmt"

func main() {
  fmt.Println("Hello World!")

  // Hello Jonathan!
  name := "Jonathan"
  fmt.Printf("Hello %s!\n", name)
  fmt.Printf("1 + 1 is %d!\n", 1+1)
  // %v for unknown variable types
  fmt.Printf("unknown variable type: %v without newline", 40.1)
}

Rust

In rust we can use the println! macro to write to output strings and variables.

fn main() {
  println!("Hello World!");
  println!("My name is {}", "Jonathan");
  println!("NOT true is {}", !true);
}

If we want to log the shape of a struct with its values we need to use a different placeholder in our log statement:

#![allow(unused)]
fn main() {
  #[derive(Debug)]
  struct Point {
    x: i32,
    y: i32,
  }

  let origin = Point { x: 5, y: 13 };

  println!("point debug: {origin:#?}")
}