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17 Threads

std::thread runs work on OS threads. spawn returns a handle; join blocks until the thread finishes and hands back its return value. move captures owned data into the closure.

Step 1 / 2

In double_in_thread, compute n * 2 on a spawned thread and return the joined result.

Hints

thread::spawn(move || n * 2) -- move takes ownership of n.
handle.join().unwrap() gives back the closure's return value.

17_threads.rs

use std::thread;

fn double_in_thread(n: i32) -> i32 {
    todo!()
}

use std::thread;

fn double_in_thread(n: i32) -> i32 {
    todo!()
}

Reset to starterCompiled in a sandbox; hidden checks must pass.

Reveal solution

use std::thread;

fn double_in_thread(n: i32) -> i32 {
    let handle = thread::spawn(move || n * 2);
    handle.join().unwrap()
}

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17 Threads