array

1. programming A collection of identically typed data items

distinguished by their indices (or "subscripts"). The number

of dimensions an array can have depends on the language but is

usually unlimited.

An array is a kind of aggregate data type. A single

ordinary variable (a "scalar") could be considered as a

zero-dimensional array. A one-dimensional array is also known

as a "vector".

A reference to an array element is written something like

A[i,j,k] where A is the array name and i, j and k are the

indices. The C language is peculiar in that each index is

written in separate brackets, e.g. A[i][j][k]. This expresses

the fact that, in C, an N-dimensional array is actually a

vector, each of whose elements is an N-1 dimensional array.

Elements of an array are usually stored contiguously.

Languages differ as to whether the leftmost or rightmost index

varies most rapidly, i.e. whether each row is stored

contiguously or each column (for a 2D array).

Arrays are appropriate for storing data which must be accessed

in an unpredictable order, in contrast to lists which are

best when accessed sequentially.

See also associative array.

2. architecture A processor array, not to be confused with

an array processor.

(1995-01-25)