HP 3000 Manuals HP 3000 Manuals
Array Subscripting
A postfix expression followed by the [ ] operator is a subscripted
reference to a single element in an array.
Syntax
postfix-expression [ expression ]
Description
One of the operands of the subscript operator must be of type pointer to
T (T is an object type), the other of integral type. The resulting type
is T.
The [ ] operator is defined so that E1[E2] is identical to (*((E1)+(E2)))
in every respect. This leads to the (counterintuitive) conclusion that
the [ ] operator is commutative. The expression E1[E2] is identical to
E2[E1].
C's subscripts run from 0 to n-1 where n is the array size.
Multidimensional arrays are represented as arrays of arrays. For this
reason, the notation is to add subscript operators, not to put multiple
expressions within a single set of brackets. For example, int x[3][5] is
actually a declaration for an array of three objects. Each object is, in
turn, an array of five int. Because of this, all of the following
expressions are correct:
x
x[i]
x[i][j]
The first expression refers to the 3 by 5 array of int. The second
refers to an array of five int, and the last expression refers to a
single int.
The expression x[y] is an lvalue.
There is no arbitrary limit on the number of dimensions that you can
declare in an array.
Because of the design of multidimensional C arrays, the individual data
objects must be stored in row-major order.
As another example, the
expression
a[i,j] = 0
looks as if array a were doubly subscripted, when actually the comma in
the subscript indicates that the value of i should be discarded and that
j is the subscript into the a array.