Rust: ownership and borrowing

question 1 of 3

Why does this not compile?

let a = String::from("kali");
let b = a;
println!("{}", a);

• a is not mutable
• The String moved to b, so a is no longer valid
• println! needs a reference
• Strings cannot be assigned

question 2 of 3

Why does the same pattern compile for integers?

let x = 5;
let y = x;
println!("{}", x);

• Integers implement Copy, so x is copied, not moved
• Integers are global
• println! copies its arguments
• It does not compile either

question 3 of 3

What happens to the String after this function call?

fn consume(s: String) { }

let name = String::from("drews");
consume(name);
println!("{}", name);

• Fine: the function borrowed it
• Error: name was moved into consume
• Fine: println! re-creates it
• Error: consume must return a value