<P> The dimension of an array is the number of indices needed to select an element . Thus, if the array is seen as a function on a set of possible index combinations, it is the dimension of the space of which its domain is a discrete subset . Thus a one - dimensional array is a list of data, a two - dimensional array a rectangle of data, a three - dimensional array a block of data, etc . </P> <P> This should not be confused with the dimension of the set of all matrices with a given domain, that is, the number of elements in the array . For example, an array with 5 rows and 4 columns is two - dimensional, but such matrices form a 20 - dimensional space . Similarly, a three - dimensional vector can be represented by a one - dimensional array of size three . </P>

Process of inserting an element in an array is called