Search results
Results From The WOW.Com Content Network
C struct data types may end with a flexible array member [1] with no specified size: struct vectord { short len ; // there must be at least one other data member double arr []; // the flexible array member must be last // The compiler may reserve extra padding space here, like it can between struct members };
The last member of a C99 structure type with more than one member may be a flexible array member, which takes the syntactic form of an array with unspecified length. This serves a purpose similar to variable-length arrays, but VLAs cannot appear in type definitions, and unlike VLAs, flexible array members have no defined size.
Bit field – Data structure that maps one or more adjacent bits; Flexible array member – C language feature in which a struct may contain as its last member an array with no specified size; Passive data structure – Another term for record; Union type – Data type that allows for values that are one of multiple different data types
Structure of arrays (SoA) is a layout separating elements of a record (or 'struct' in the C programming language) into one parallel array per field. [1] The motivation is easier manipulation with packed SIMD instructions in most instruction set architectures, since a single SIMD register can load homogeneous data, possibly transferred by a wide internal datapath (e.g. 128-bit).
With arrays, this means that the dimensions of the array must be present in its declaration, and that the type of the elements must be completely defined. For structs and unions, this means that there must be a member list of completely defined types. For example, consider the following two source files:
It is also possible to tell most C and C++ compilers to "pack" the members of a structure to a certain level of alignment, e.g. "pack(2)" means align data members larger than a byte to a two-byte boundary so that any padding members are at most one byte long.
A class in C++ is a user-defined type or data structure declared with any of the keywords class, struct or union (the first two are collectively referred to as non-union classes) that has data and functions (also called member variables and member functions) as its members whose access is governed by the three access specifiers private, protected or public.
It evaluates to the offset (in bytes) of a given member within a struct or union type, an expression of type size_t. The offsetof() macro takes two parameters, the first being a structure or union name, and the second being the name of a subobject of the structure/union that is not a bit field. It cannot be described as a C prototype. [1]