How to Use println! Debugging in Rust Effectively

Use the println! macro with curly braces to print variable values directly to the console for immediate debugging.

use std::io;

fn main() {
    let secret_number = 42;
    println!("The secret number is: {secret_number}");

    let mut guess = String::new();
    io::stdin()
        .read_line(&mut guess)
        .expect("Failed to read line");

    println!("You guessed: {guess}");
}

The println! macro is a quick way to print text and variable values to your screen while your program runs. Think of it like a temporary signpost that tells you exactly what data your code is holding at that specific moment. You use it to spot errors or verify that your logic is working before you remove it.