Rust - lesson 2 | HackIndia Skills

Rust - lesson 2 | HackIndia Skills | HackIndia

Example

Move versus borrow

This version moves name into print_name. After that, main cannot use name again.

fn print_name(name: String) {
    println!("Project: {}", name);
}

fn main() {
    let name = String::from("fees-tracker");
    print_name(name);
    println!("Running {}", name); // error: name was moved
}

Example

Borrow instead

If the function only reads the value, take &str or &String. Prefer &str for text input because it works with String and string literals.

fn print_name(name: &str) {
    println!("Project: {}", name);
}

fn main() {
    let name = String::from("fees-tracker");
    print_name(&name);
    println!("Running {}", name); // works
}

Common mistake

Cloning too early

Beginners often add .clone() everywhere to silence errors. It works, but it hides the real ownership issue and can waste memory.

Clone only when you truly need two owned copies. In most CLI code, a reference is enough for printing, checking, parsing, or matching.

let command = String::from("add");

// Usually avoid this:
show_command(command.clone());

// Prefer this when show_command only reads:
show_command(&command);

Own values without confusion

One thing

Why this matters

Move versus borrow

Borrow instead

Choose the parameter

Cloning too early

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