How Ownership Works

Ownership in Rust

Every value in Rust has exactly one owner. When the owner goes out of scope, the value is dropped.

The Three Rules

1. Each value has a single owner variable
2. There can only be one owner at a time
3. When the owner goes out of scope, the value is dropped

Move Semantics

let s1 = String::from("hello");
let s2 = s1; // s1 is MOVED into s2
// println!("{s1}"); // ERROR: s1 is no longer valid
println!("{s2}"); // OK

Unlike garbage-collected languages, Rust doesn't copy heap data by default. Assignment moves ownership.

Stack vs. Heap

• Stack types (i32, bool, f64) implement Copy — assignment copies the bits
• Heap types (String, Vec<T>) are moved — only the pointer is copied, original is invalidated

The Clone Trait

To explicitly duplicate heap data:

let s1 = String::from("hello");
let s2 = s1.clone(); // deep copy
println!("{s1} {s2}"); // both valid

Why This Matters for Solana

Solana programs are written in Rust. Understanding ownership prevents common bugs like use-after-free and double-free — without needing a garbage collector eating into your compute units.