Derived types and allocatable - comp.lang.fortran

Message from discussion Derived types and allocatable

Gib Bogle

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More options May 6, 12:01 am

Newsgroups: comp.lang.fortran

From: Gib Bogle <g.bo...@auckland.no.spam.ac.nz>

Date: Tue, 06 May 2008 16:01:28 +1200

Local: Tues, May 6 2008 12:01 am

Subject: Derived types and allocatable

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I am still trying to get to grips with how one should copy derived types that contain allocatable
arrays. The test program below, when compiled with IVF 10.1, displays the cdata array contents
correctly, but gives an access violation in the deallocation step. If I neglect the deallocation
there are no error messages. When compiled on IBM Linux (with xlf95_r) it runs without errors. But
running my real program, in which I am presumably doing something wrong, on the IBM machine there is
no error until the deallocation step, which is carried out exactly as in the code below, and then I
get a multitude of error messages like

glibc detected *** double free or corruption (!prev): 0x100a0220
and
glibc detected *** corrupted double-linked list: 0x1009db18

Is it OK to do

cell2(i) = cell1(i)

when cell2(i)%cdata has not been allocated, or do I first need to ensure that %cdata is allocated?

!----------------------------------------------------------------
program main
integer :: csize(2) = (/10,100/)
integer :: k, i
type cell_type
integer :: ID
real, allocatable :: cdata(:)
end type
type(cell_type), allocatable :: cell1(:),cell2(:)

allocate(cell1(2))
allocate(cell2(2))

do i = 1,2
allocate(cell1(i)%cdata(csize(i)))
do k = 1,csize(i)
cell1(i)%cdata(k) = k
enddo
enddo

do i = 1,2
cell2(i) = cell1(i) ! cell2(i)%cdata not allocated
write(*,*) cell2(i)%cdata
enddo

do i = 1,2
do k = 1,csize(i)
if (allocated(cell1(i)%cdata)) then
deallocate(cell1(i)%cdata)
endif
enddo
if (allocated(cell1)) then
deallocate(cell1)
endif
enddo
do i = 1,2
do k = 1,csize(i)
if (allocated(cell2(i)%cdata)) then
deallocate(cell2(i)%cdata)
endif
enddo
if (allocated(cell2)) then
deallocate(cell2)
endif
enddo

end
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