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José Luis Gómez Dans wrote: > > Hi, > I have a problem (getting SEGFAULTS where things should be as > smooth as silk). I have a derived type which has a number of allocatable > arrays (specified as pointers): > type MyType > real :: a, b, c > complex,pointer,dimension(:,:) :: S1, S2, S3 > end type MyType > > I put some data into my allocated arrays without any problems. > So at this point, S1, S2 and S3 all point to allocated areas of memory > and data sits there quite happily. > > I then pass my type to a subroutine: > subroutine MySubroutine(InstanceOfMyType) > type(MyType) :: InstanceOfMyType > type(MyType) :: TemporaryType > > In this subroutine, I have a temporary type, which is just a > copy of my argument. What I do is to ALLOCATE some memory for S1, S2 and > S3 in this new temporary type. The copy of the passed argument is done > simply by an equal sign: TemporaryType = InstanceOfMyType. I believe this is your problem. Intrinsic assignment (which this is unless you've defined an assignment overload for MyType) does a POINTER assignment for internal components What you have is equivalent to TemporaryType%S1 => InstanceOfMyType%S1 This doesn't copy the actual data in the S1 array; it makes TemporaryType%S1 point to that same area in momory that InstanceOfMyType%S1 points to. When you deallocate TemporaryType%S1 you are also deallocating InstanceOfMyType%S1 (technically I suppose you are making TemporaryType%S1 be undefined). The assignment also effectively causes the memory you allocated to TemporaryType%S1 become unavailable. Hard to say what else is going on, but when you try to put data into InstanceOfMyType%S1 I think you are actually using a pointer that does not point to anything. You either need to define an overload that copies the contents of the arrays, or do component assignment term by term. Hope this helps Dick Hendrickson >The first > thing I noticed was that the scalar structure members (a, b and c) are > all fine. Because I wanted to change the size of the arrays, I > deallocate S1, S2 and S3 in TemporaryType and allocate them to something > new. I was a bit worried about this, as this is a pointer pointing to a > new area of memory. However, it seems to work. Then I do play around > with that and eventually copy some data to the starting arrays. This all > works fine. Except that the program segfaults returning to the point > where it branched out to the subroutine. > > I haven't got a clue why this happens, as everything in the > subroutine works, and the data that is copied into the starting arrays > is copied by value, not just to a pointer or something like that. > > Can anyone shed any light? > > José > -- > José L Gómez Dans PhD student > Tel: +44 114 222 5582 Radar & Communications Group > FAX; +44 870 132 2990 Department of Electronic Engineering > University of Sheffield UK