How to Return Ownership from a Function in Rust

To return ownership from a function in Rust, define the function to return the type (e.g., String) and place the variable as the final expression without a semicolon. This moves the value out of the function scope and into the caller.

fn gives_ownership() -> String {
    let some_string = String::from("yours");
    some_string
}

fn takes_and_gives_back(a_string: String) -> String {
    a_string
}

fn main() {
    let s1 = gives_ownership();
    let s2 = String::from("hello");
    let s3 = takes_and_gives_back(s2);
}

Returning ownership means passing the responsibility for managing a piece of data from one part of your code to another. When a function returns a value like a String, it hands over the 'deed' to that memory, and the original variable inside the function is no longer valid. Think of it like handing a physical book to someone; once they have it, you can no longer read it yourself.