JohnCampbell
Joined: 16 Feb 2006
Posts: 2554
Location: Sydney
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 Posted: Fri Sep 18, 2009 4:25 am Post subject: Use of TYPE arrays |
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Paul,
Following on from the question I asked previously, the following example appears to show that the compiler generates a temporary array, when providing part of a Type data set. Presumably the temporary array is on the stack ? With large type data sets, could this lead to stack overflow problems ? Or have I mis-understood my example ?
| Code: | ! Last change: JDC 18 Sep 2009 9:03 am
module my_data
integer*4, parameter :: mxnode = 10
TYPE Coordinate_Record
real*8 X
real*8 Y
real*8 Z
integer*4 fixity(6)
END TYPE Coordinate_Record
type (Coordinate_record) nodes(mxnode)
end module
use my_data
integer*4 index(mxnode), i
do i = 1,mxnode
call random_number (nodes(i)%x)
call random_number (nodes(i)%y)
call random_number (nodes(i)%z)
end do
call dsort@ (index, nodes%z, mxnode) ! this works
do i = 1,mxnode
write (*,'(2i5,3f10.6)') i, index(i), nodes(index(i))%x, nodes(index(i))%y, nodes(index(i))%z
end do
call test_argument_1 (nodes%z, mxnode) ! change is lost
write (*,1000) 'type',nodes(10)%z, ' change to nodes(i)%z lost'
call test_argument_2 (nodes%z, mxnode) ! change is updated
write (*,1000) 'type',nodes(10)%z, ' change to nodes_z(i) updated'
1000 format (a,f10.6,a)
end
subroutine test_argument_1 (nodes_z, num)
use my_data
real*8 nodes_z(num)
integer*4 num, i
i = 10
write (*,1000) 'type',nodes(i)%z, ': Argument',nodes_z(i)
nodes(i)%z = i
write (*,1000) 'type',nodes(i)%z, ': Argument',nodes_z(i)
return
1000 format (2(a,f10.6))
end
subroutine test_argument_2 (nodes_z, num)
use my_data
real*8 nodes_z(num)
integer*4 num, i
i = 10
write (*,1000) 'type',nodes(i)%z, ': Argument',nodes_z(i)
nodes_z(i) = i
write (*,1000) 'type',nodes(i)%z, ': Argument',nodes_z(i)
return
1000 format (2(a,f10.6))
end
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