Ownership, moves and cleanup

A student name stored in String owns a growable text buffer. Ownership tells Rust who is responsible for that value. Moving the String transfers that responsibility; it does not make a second independently owned text buffer. This explains many compiler errors that initially feel surprising.

A String has a small representation containing information about its allocated text. Assigning it to another binding normally moves the value. The previous binding can no longer be used. When the owner goes out of scope, Rust drops the value and releases its owned resources. Shared ownership wrappers are deliberate alternatives, not exceptions you get from ordinary assignment.

Connect this idea with copy values and deliberate cloning and references and read-only borrowing.

Save the complete source as main.rs in the Rust environment. No standard input is needed.

Rust 2024 · complete program

fn main() {
  let original = String::from("Diya");
  let registered = original;
  println!("Registered: {registered}");
}

Expected output

Registered: Diya

Follow the execution

Original first owns the String. The assignment transfers ownership to registered without cloning the text buffer. Printing borrows registered for formatting. At the end of main, registered is dropped; original is no longer a usable owner.

Try the complete program in the Rust compiler. For tests, Cargo commands and local files, use the specified local environment.

A parameter declared as name: String takes ownership when called with an owned String. Unless the function returns that value, the caller cannot use the original binding afterward. A parameter name: &str instead borrows readable text. Choose the signature based on whether the operation must retain ownership or only inspect a value.

Stack and heap describe storage strategies. A String’s small representation is often held in a local variable while its growable text is allocated separately. A move transfers ownership; it is not a promise that the compiler physically relocates all text bytes.

Your task: Can you print original after assigning it to registered?

Rust 2024 · complete program

fn main() {
  let original = String::from("Diya");
  let registered = original;
  println!("Registered: {registered}");
}

Worked answer

No. The String was moved, so using original afterward fails to compile. Borrow when another operation only needs to read it, or clone deliberately when an independent value is needed.

The school-register analogy describes responsibility, not a real person physically relocating. Copy types behave differently, and ownership is not identical to immutability. Borrowing permits temporary access without transferring responsibility.

No. The String was moved, so using original afterward fails to compile. Borrow when another operation only needs to read it, or clone deliberately when an independent value is needed. The school-register analogy describes responsibility, not a real person physically relocating.

Further reading: the official Rust Book on ownership, moves and cleanup.