ALLOCATE

Syntax

ALLOCATE (object[(s-spec)] [,object[(s-spec[,s-spec]...)] ]...[, alloc-opt])

object	Is the object to be allocated. It is a variable name or structure component, and must be a pointer or allocatable array. The object can be of type character with zero length.
s-spec	Is a shape specification in the form [lower-bound:]upper-bound. Each bound must be a scalar integer expression. The number of shape specifications must be the same as the rank of the object.
alloc-opt	(Output) Is one of the following:
STAT=sv	sv is a scalar integer variable in which the status of the allocation is stored.
ERRMSG=ev	ev is a scalar default character value in which an error condition is stored if such a condition occurs.

Description

A bound in s-spec must not be an expression containing an array inquiry function whose argument is any allocatable object in the same ALLOCATE statement; for example, the following is not permitted:

INTEGER ERR

INTEGER, ALLOCATABLE :: A(:), B(:)

...

ALLOCATE(A(10:25), B(SIZE(A)), STAT=ERR) ! A is invalid as an argument

! to function SIZE

If a STAT variable or ERRMSG variable is specified, it must not be allocated in the ALLOCATE statement in which it appears. If the allocation is successful, the variable is set to zero. If the allocation is not successful, an error condition occurs, and the variable is set to a positive integer value (representing the run-time error); the ERRMSG variable contains the error condition. If no STAT variable is specified and an error condition occurs, program execution terminates.

To release the storage for an allocated array, use DEALLOCATE.

To determine whether an allocatable array is currently allocated, use the ALLOCATED intrinsic function.

To determine whether a pointer is currently associated with a target, use the ASSOCIATED intrinsic function.

Example

!Method for creating and allocating deferred shape arrays.

INTEGER,ALLOCATABLE::matrix(:,:)

REAL, ALLOCATABLE:: vector(:)

. . .

ALLOCATE (matrix(3,5),vector(-2:N+2))

. . .

The following shows another example of the ALLOCATE statement:

INTEGER J, N, ALLOC_ERR

REAL, ALLOCATABLE :: A(:), B(:,:)

...

ALLOCATE(A(0:80), B(-3:J+1, N), STAT = ALLOC_ERR)