Declares an allocatable array with deferred shape.
Syntax
The
syntax of a type declaration statement with the ALLOCATABLE attribute is:
type, attrib-list :: entity-list |
- type
is a valid type specification (INTEGER, REAL, LOGICAL, CHARACTER, TYPE(type-name), etc.), as described in Chapter 5 “Data
types and data objects”.
- attrib-list
is a comma-separated list of attributes including ALLOCATABLE and optionally those attributes compatible with
it, namely:
Table 10-2 Title not available (ALLOCATABLE (statement and attribute))
DIMENSION | PUBLIC | TARGET |
PRIVATE | SAVE | |
- entity-list
is a comma-separated list of entities. Each entity
is of the form:
array-name [( deferred-shape-spec-list )] |
If ( deferred-shape-spec-list ) is omitted, it must be specified in another declaration
statement.
- array-name
is the name of an array being given the attribute ALLOCATABLE.
- deferred-shape-spec-list
is a comma-separated list of colons, each colon
representing one dimension. Thus the rank of the array is equal
to the number of colons specified.
The syntax of the ALLOCATABLE statement is:
ALLOCATABLE [::] array-name [(deferred-shape-spec-list)] |
[,array-name [(deferred-shape-spec-list)]]... |
If (deferred-shape-spec-list) is omitted from the ALLOCATABLE statement, it must be specified in another declaration
statement, such as a type or DIMENSION statement.
The ALLOCATED intrinsic inquiry function is described in “ALLOCATED(ARRAY)”. It can be used to
determine whether an allocatable array is currently allocated.
Description
The ALLOCATABLE attribute or statement is used to declare an array
whose extents in all its dimensions will be specified when an ALLOCATE statement is executed at run-time; for this reason
it is known as “deferred-shape”. When an allocatable
array is declared, only its name and rank are given.
Examples
The following statements declare a rank-one deferred-shape
array and illustrate its use with different extents.
! mls is deferred shape.
INTEGER, ALLOCATABLE :: mls(:)
ALLOCATE (mls (3)) ! Allocate 3 elements.
DEALLOCATE (mls) ! mls is no longer allocated
ALLOCATE (mls (-n:n)) ! Allocate with different extent |
Related statements
ALLOCATE and DEALLOCATE
Related concepts
See “Allocatable
arrays” for
more information about allocatable arrays and the conditions applying
to their use.
Array pointers provide a more general mechanism for the manipulation
of deferred-shape arrays; see “Array
pointers”.
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