Dereferencing

Dereferencing is a fundamental operation in many programming languages that retrieves the value stored at an address or through an indirect handle such as a pointer, reference, or iterator. It converts a reference to the actual value it refers to, or, in languages that expose pointers, uses an explicit operator to access or assign through the pointed-to object.

In languages with explicit pointers, such as C and C++, dereferencing is typically done with the asterisk operator. Given a pointer p to a value, *p yields the value stored at that address (and can be assigned to, if p is non-const). The member of a pointed-to structure is often accessed with the arrow operator, p->field, which is equivalent to (*p).field. Dereferencing a null or invalid pointer results in undefined behavior or runtime errors and is a major source of bugs.

In higher-level languages that use references rather than pointers, dereferencing is usually implicit. For example, Java and C# expose object references without an explicit dereference operator; the runtime handles the indirection when methods or fields are accessed. Some languages provide explicit pointer-like features in unsafe or low-level contexts, where dereferencing remains possible but restricted.

In C++, dereferencing also applies to iterators and smart pointers: *it yields the element the iterator points to, and *ptr works with smart pointers to access the underlying object.

In Rust, dereferencing is supported by the dereference operator and by automatic deref coercions, enabling seamless access across Box<T>, &T, and other pointer-like types.

Overall, dereferencing is the process of obtaining the value behind a reference or pointer, with syntax and safety guarantees varying by language.