Deallocates allocatable arrays and pointer targets.
Syntax
DEALLOCATE (alloc-obj-list[, STAT=scalar-int-var]) |
- alloc-obj-list
is a comma-separated list of pointers or allocatable
arrays.
- STAT=scalar-int-var
returns the error status after the statement executes.
If given, it is set to a positive value if an error is detected,
and to zero otherwise. If there is no status variable, the occurrence
of an error causes the program to terminate.
Description
The DEALLOCATE
statement deallocates allocatable arrays and pointer targets, making
the memory available for reuse. A specified allocatable array then
becomes not allocated (as reported by the ALLOCATED
intrinsic), while a specified pointer becomes disassociated (as
reported by the ASSOCIATED
intrinsic).
An error occurs if an attempt is made to deallocate an allocatable
array that is not currently allocated or a pointer that is not associated.
Errors in the operation of DEALLOCATE
can be reported by means of the optional STAT=
specifier.
You can deallocate an allocatable array by specifying the
name of the array with the DEALLOCATE
statement. You cannot deallocate a pointer that points to an object
that was not allocated.
Some or all of a target associated with a pointer by means
of the ALLOCATE
statement can also be associated subsequently with other pointers.
However, it is not permitted to deallocate a pointer that is not
currently associated with the whole of an allocated target object.
Deallocation of a pointer target causes the association status
of any other pointer associated with all or part of the target to
become undefined. When a pointer is deallocated, its association
status becomes disassociated, as if a NULLIFY
statement had been executed.
Examples
The following example declares a complex array with the POINTER
attribute. The ALLOCATE
statement allocates target space to the array at run-time; the amount
is determined by the input values to the READ
statement. Later in the program, the DEALLOCATE
statement will recover the space.
COMPLEX, POINTER :: hermitian (:, :)
...
READ *, m, n
ALLOCATE (hermitian (m, n))
...
DEALLOCATE (hermitian, STAT = ierr) |
Related statements
ALLOCATABLE,
ALLOCATE, NULLIFY,
and POINTER
Related concepts
For related information, see the following:
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