Pointertypes

Pointertypes are types whose values represent memory addresses pointing to values of a given type. They enable indirect access to data and are central to low-level memory manipulation in many programming languages. A pointer type is distinct from the value it points to and from ordinary non-pointer types.

Across languages, syntax and rules for pointer types vary. In C and C++, a pointer to T is written as T*, and a pointer value can be null. Pointers support operations such as dereferencing to read or write the pointed-to value and, in some languages, pointer arithmetic to move through memory. In Rust, the language enforces safety through references, such as &T and &mut T, which are checked by the borrow checker, while raw pointers, *const T and *mut T, exist in unsafe blocks for low-level use.

Common semantics include taking the address of a value, dereferencing to access the pointed-to object, and understanding the size and alignment of the pointer itself, which are typically independent of the pointed-to type. Pointer usage interacts closely with memory management, including ownership, lifetimes, and validity. Issues such as null or dangling pointers, use-after-free, and memory leaks are common risks in languages that expose raw pointers, while safer languages provide mechanisms like automatic memory management or strict borrowing rules.

Pointers play a practical role in implementing data structures (linked lists, trees), interfacing with system APIs, and performing efficient array or buffer manipulation. They are also a key concept in low-level programming, enabling explicit control over memory layout and performance considerations. Across languages, pointer types thus form a fundamental tool for indirect data access, memory management, and systems programming, while differing in safety guarantees and ergonomic complexity.