println macro

The printl macro

Macros expand into additional code
println "Prints" (displays) information to the terminal
Useful for debugging

Tokens

We use the {:?} token to mark where a variable should be displayed in the println! with the ":?" marking it as a debug statement that shouldn't be visible to the end user. We can also use variables directly in the token

If we want to print something that will be visible to the end user, we can remove the ":?" and just use "{}", <variable> or "{<variable>}"

let life = 42;
println!("hello");
println!("{:?}", life);
println!("{:?} {:?}", life, life);
println!("the meaning id {:?}", life);
println!("{life:?}")
println!("{life}")

Important

The exclamation mark in println!() tells the program that we're running a macro not a function