Re-size array within a subroutine

sang186

Thu, 11/01/2012 - 09:23

I am trying to implement a push_back routine as below.

SUBROUTINE push_back(array, val)
INTEGER,DIMENSION(:), ALLOCATABLE :: tmp_arr
INTEGER, DIMENSION(:) :: array
INTEGER val
ALLOCATE(tmp_arr(0 : SIZE(array)))
tmp_arr(0:(SIZE(array)-1))=array
tmp_arr(SIZE(array)) = val
DEALLOCATE(array)
ALLOCATE(array(0:SIZE(tmp_arr)-1))
CALL move_alloc(tmp_arr, array)
END SUBROUTINE push_back

On resizing an allocatable array (declared ALLOCATABLE in the calling subroutine) , I get the following compile errors

error #6724: An allocate/deallocate object must have the ALLOCATABLE or POINTER attribute. [ARRAY]
error #8195: The argument to the MOVE_ALLOC intrinsic subroutine shall be an allocatable object. [MOVE_ALLOC]

I want the resize to work such that the data that is passed is not lost. However, by making array ALLOCATABLE within the subroutine , I would lose the existing data.
Any help with this would be great.

8 posts / 0 new

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Les Neilson

Thu, 11/01/2012 - 09:30

INTEGER, DIMENSION(:), ALLOCATABLE :: array

you forgot to tell the compiler that "array" was also allocatable.
Les

D.W. van Meeuwen

Thu, 11/01/2012 - 09:33

Is this something that you want to reach?

SUBROUTINE UTIL_ADDTO_ARRAYint2Allocarray(ToBeAdded,IntegerArray) !{
! This subroutine adds a single value to the end of an integer array.
IMPLICIT NONE
!** HEADER VARIABLES/ARGUMENTS
INTEGER, INTENT(IN) ::ToBeAdded
INTEGER, ALLOCATABLE ::IntegerArray(:)
!*****************************************************************************
!** LOCAL VARIABLES
INTEGER ::NewSize
INTEGER ::OldSize
INTEGER, ALLOCATABLE ::CopyArray(:)
!*************************************************************************

IF (allocated(IntegerArray)) THEN
OldSize=size(IntegerArray)
NewSize = OldSize + 1
ALLOCATE(CopyArray(NewSize))
CALL MOVE_ALLOC(CopyArray, IntegerArray)
IntegerArray(NewSize) = ToBeAdded
ELSE
ALLOCATE(IntegerArray(1))
IntegerArray(1)=ToBeAdded
ENDIF

ENDSUBROUTINE UTIL_ADDTO_ARRAYint2Allocarray !}

Making the array allocatable within the subroutine does not lose your data.

regards,
Dirk

sang186

Thu, 11/01/2012 - 09:36

On making array 'ALLOCATABLE ' with

INTEGER, DIMENSION(:), ALLOCATABLE :: array

I would lose its existing allocation and its data and I would like to retain that.

mecej4

Thu, 11/01/2012 - 11:12

Best Reply

Merely declaring an argument array to be ALLOCATABLE does not change its allocation status or contents.

The following program works fine


program tpush

IMPLICIT NONE

INTEGER, DIMENSION(:), ALLOCATABLE :: ivec

INTEGER :: val=4

ALLOCATE(ivec(3))

ivec=(/1,2,3/)

call push_back(ivec, val)

write(*,'(10I4)')ivec
contains

SUBROUTINE push_back(array, val)

    INTEGER,DIMENSION(:), ALLOCATABLE :: tmp_arr

    INTEGER, DIMENSION(:),ALLOCATABLE :: array

    INTEGER val

    ALLOCATE(tmp_arr(0 : SIZE(array)))

    tmp_arr(0:(SIZE(array)-1))=array

    tmp_arr(SIZE(array)) = val

    DEALLOCATE(array)

    ALLOCATE(array(0:SIZE(tmp_arr)-1))

    CALL move_alloc(tmp_arr, array)

END SUBROUTINE push_back

END PROGRAM tpush

The program prints out

   1   2   3   4

[Complaints re ISDN forum software: (i) The program source code above appears single-spaced in edit mode, but appears mostly double spaced in browse mode; (ii) It is confusing when the OP replies to other people's responses and there are no response numbers to provide information on which response is being replied to .]

sang186

Thu, 11/01/2012 - 10:00

Sorry, It was my bad.

I had overlooked the allocation of the array with a zero index in the calling function . It works now.
@Les & @Dirk - Thank you very much for the inputs.

Sangeetha

sang186

Thu, 11/01/2012 - 10:03

It was totally my bad. Thank you very much, mecej4.

Les Neilson

Fri, 11/02/2012 - 00:58

That's ok - we all make mistakes. Glad it now works
Les

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Re-size array within a subroutine

Re-size array within a subroutine

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