Rust for C-Programmers

19.9 Summary

Rust’s smart pointers provide powerful patterns that extend beyond simple stack allocation and references:

• Box<T>: Heap-allocated values with exclusive ownership.
• Rc<T> and Arc<T>: Enable multiple ownership via reference counting (single-threaded or thread-safe).
• Interior Mutability (Cell<T>, RefCell<T>, OnceCell<T>): Allow controlled mutation through apparently immutable references.
• Weak<T>: Non-owning references that prevent reference cycles.

Together, these options offer precise control over memory ownership, sharing, and mutation. By combining Rust’s compile-time safety with targeted runtime checks (when necessary), smart pointers prevent many classic memory errors—dangling pointers, double frees, and memory leaks—while still providing the flexibility required for complex data structures and concurrency patterns.

The judicious use of these smart pointers enables Rust programmers to solve problems that would be difficult or error-prone in languages like C, while maintaining performance characteristics that rival manually managed memory systems.