Chapter 6: Ownership, Borrowing, and Memory Management

In C, manual memory management is a central aspect of programming. Developers allocate and deallocate memory using malloc and free, which provides flexibility but is notoriously prone to errors like memory leaks, dangling pointers, and use-after-free bugs. C++ introduced RAII (Resource Acquisition Is Initialization) and smart pointers to automate resource management, reducing some risks. Many higher-level languages (Java, Python, Go, etc.) employ garbage collection (GC), which simplifies memory management significantly but often introduces runtime overhead and non-deterministic pauses, making it less suitable for performance-critical systems or embedded environments.

Rust presents a unique alternative: compile-time memory safety without a garbage collector. It achieves this through a system of ownership, borrowing, and lifetimes, enforced by the compiler. This approach ensures memory safety with minimal runtime overhead, making Rust a compelling choice for systems programming.

This chapter introduces these core concepts, primarily using Rust’s String type as an example. Its dynamic, heap-allocated nature makes it ideal for illustrating ownership principles clearly. We’ll compare Rust’s mechanisms with C/C++ idioms where helpful. We will also briefly touch upon Rust’s smart pointers and the unsafe keyword for scenarios requiring more manual control or C interoperability, deferring deep dives to later chapters (Chapters 19 and 25).