Curriculum Ownership & borrowing Moves and Copy exercise 2 · mcq-explain

Moves and Copy

rustc emits this diagnostic on the program below. Pick the line that's a MOVE (not a copy, borrow, or unrelated assignment). error[E0382]: borrow of moved value: name --> src/main.rs:3:20 | 1 | let name = String::from("paul"); 2 | let owner = name; 3 | println!("{}", name); | ^^^^ value borrowed here after move

let name = String::from("paul"); — that's the original construction, not a move.

println!("{}", name); — that's where the error surfaces, but the MOVE happened on the previous line.

let owner = name; — assignment moves the String out of name into owner.

String::from("paul") — that allocates but doesn't move anything yet.

About this theme

TypeScript variables point at values managed by a garbage collector; Rust bindings own values unless the type is Copy. This theme makes moves concrete before references appear. Planned exercises: 1. choose which binding owns a String. 2. recognise a move. 3. recognise a Copy integer. 4. fill the line that avoids using a moved value. 5. fill a clone() only where an owned duplicate is intended. 6. write a function that takes ownership. 7. write a function that returns ownership. 8. translate TS object passing into Rust moves. 9. fix a use-after-move compiler error.