HP Fortran Programmer's Reference (September 2007)

Arrays

Array sections

Chapter 370

! The arrays x, y, and z now have the following values:

! x y z

! 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 3 3 3

! 0 0 0 0 0 0 0 2 0 2 0 2 0 0 3 3 3 3

! 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0

In the following example of an array substring, the variable dates(5:10) is an array section

that includes elements 5 through to 10 of the parent array dates, and the variable

dates(5:10)(8:11) is also an array section of the array dates but only contains the last 4

character positions of the elements 5 through to 10.

CHARACTER(11) :: dates(20)

dates(5:10)(8:11) = ”1776”

Vector subscripts

A vector subscript is any expression that results in a rank-one array with integer value.

The values of the array select the corresponding elements of the parent array for a given

dimension. Vector subscripts can describe an irregular pattern and may be useful for indirect

array addressing. For example, if v represents a rank-one integer array initialized with the

values 4, 3, 1, 7, then the array section a(v) is a rank-one array composed of the array

elements a(4), a(3), a(1), and a(7)—in that order.

Vector subscripts are commonly speciﬁed using array constructors, which are described in the

next section. For example, the expressions a(v) and a((/ 4, 3, 1, 7/)) reference the same

section of the array a.

Vector subscripts may not appear:

• On the right hand side of a pointer assignment statement.

• In an I/O statement as an internal ﬁle.

• As an actual argument that is associated with a dummy argument declared with

INTENT(OUT) or INTENT(INOUT) or with no INTENT.

A vector subscript may specify the same element more than once. When a vector subscript of

this form speciﬁes an array section, the array section is known as a

many-one array

section

. An example of a

many-one array section

is:

a( (/ 4, 3, 4, 7/) )

where element 4 has been selected twice. A many-one array section may not appear in either

an input list or on the left-hand side of an assignment statement.

The following example, vector_sub.f90, illustrates an array section using a section subscript

list.