Array Data Structure In computer science, an array data structure or simply array is a data structure consisting of a collection of elements (values or variables), each identified by one or more integer indices, stored so that the address of each element can be computed from its index tuple by a simple mathematical formula. For example, an array of 10 integer variables, with indices 0 through 9, may be stored as 10 words at memory addresses 2000, 2004, 2008, … 2036 (this memory allocation can vary because some computers use other than 4 bytes to store integer type variables); so that the element with index i has address 2000 + 4 × i.
Array structures are the computer analog of the mathematical concepts of vector, matrix, and tensor. Indeed, an array with one or two indices is often called a vector or matrix structure, respectively. Arrays are often used to implement tables, especially lookup tables; so the word table is sometimes used as synonym of array.
Arrays are among the oldest and most important data structures, and are used by almost every program and are used to implement many other data structures, such as lists and strings. They effectively exploit the addressing machinery of computers; indeed, in most modern computers (and many external storage devices), the memory is a one-dimensional array of words, whose indices are their addresses. Processors, especially vector processors, are often optimised for array operations.
Arrays are useful mostly because the element indices can be computed at run time. Among other things, this feature allows a single iterative statement to process arbitrarily many elements of an array. For that reason, the elements of an array data structure are required to have the same size and should use the same data representation. The set of valid index tuples and the addresses of the elements (and hence the element addressing formula) are usually fixed while the array is in use.
