struct

A struct is a composite data type that groups together related data items under a single name. Each member has a name and a type, and the struct as a whole is treated as a single value that can be stored, passed, or returned as a unit. Structs are commonly used to model entities with multiple attributes, such as points, dates, or configuration records.

In C, a struct is declared with the struct keyword and defined as a fixed layout of fields. C programmers often use typedef to create a convenient alias for the struct type. In C++, structs and classes are virtually the same; the only practical difference is the default access level—struct members are public by default, whereas class members are private.

Other languages use the term struct with differences in semantics. In Go, a struct defines a named, fixed-layout type that is a value type and zero-initializes. Methods can be associated with a struct type. In Rust, there are named-field structs and tuple structs; they participate in ownership and borrowing rules, and Rust allows trait implementations and pattern matching on struct instances.

Common considerations include memory layout and padding, which may affect size and alignment, and the potential need for packing or platform-specific attributes. Structs are frequently used for data interchange formats, APIs, and as simple containers for related fields. To model behavior, languages typically provide mechanisms such as methods, functions, or associated operations that work alongside the struct type.