Rust's ownership model: passing a value transfers ownership (move); taking a `&value` lets you read without taking ownership; `&mut value` lets you modify without taking ownership. Only one mutable borrow OR many immutable borrows at a time.
Rust
fn takes_ownership(s: String) {
println!("owned: {s}");
} // s is dropped here
fn borrows(s: &String) {
println!("borrowed: {s}");
} // s is NOT dropped — caller still owns it
fn borrows_mut(s: &mut String) {
s.push_str(" — modified");
}
fn main() {
let mut s = String::from("hello");
borrows(&s); // OK — many immutable borrows allowed
borrows(&s); // OK
borrows_mut(&mut s); // mutable borrow — only one at a time
println!("{s}"); // "hello — modified"
takes_ownership(s); // moves s
// println!("{s}"); // ❌ compile error: s was moved
}Save your own code snippets
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