Understanding Ownership

Snippet

Understanding Ownership

Rust uses an ownership system to manage memory efficiently without garbage collection. When you assign s1 to s2, ownership of the data moves to s2, and s1 is no longer valid. This prevents double-free errors. For read-only access, you can borrow a reference with &, which allows multiple references without transferring ownership.

snippet.rs
rust
fn main() {
    let s1 = String::from("hello");
    let s2 = s1;
    
    // println!("{}", s1); // Error: s1 is no longer valid
    println!("{}", s2);
    
    let s3 = String::from("world");
    let s4 = &s3;
    
    println!("{}", s3); // s3 is still valid, s4 just borrows it
    println!("{}", s4);
}

Breakdown

let s1 = String::from("hello");

Creates a String owned by s1

let s2 = s1;

Ownership moves to s2, s1 is now invalid

let s4 = &s3;

Creates a borrowing reference, s4 does not own the data

println!("{}", s3);

s3 is still valid because only a reference was borrowed

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Understanding Ownership

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