Array element does not inherit the POINTER attr from its parent array

Question

I have to classify millions of numbered triangles into different squares (suppose there are 1000 squares) by some method, but I don't know how many triangles that belong to some square before judgement. So I need 1000 linked lists so that I can store the number of relevant triangles in any length.

But it seems that I can't decalre a 1000-element head array to create 1000 linked lists in Fortran (Intel Visual Fortran 2011), and there is an error:

LoopLinkedList.for(34): error #7121: A ptr dummy may only be argument associated with a ptr, and this array element or section does not inherit the POINTER attr from its parent array. [CURRENT]

Here is code of my testing program:

   module global
       type node
         integer i
          type(node) ,pointer ::next
       end type node
   end module global 


   program  LinkedList
   use global

   integer k
    interface 
    subroutine insertItem(pos,item)
     use global
     implicit none 
     type(node) ,pointer ::pos,item
    end subroutine insertItem
    end interface 

   type(node), pointer::item,head(:),current(:)


   allocate(head(1000))
   allocate(current(1000))
    head(1) = node(1,head(1))
   current(1)=head(1)


    do k  =2,10
    allocate(item)
    !allocate(current%next) 
    item%i = k
    call insertItem(current(1),item)
   current(1) =item
    end do



    k =current(1)%i
    do while(.true.) 
      write(*,*) current(1)%i
     if(.not.associated(current(1)%next)) exit
      current(1) =current(1)%next
      if(current(1)%i.eq.k)exit
    end do

    deallocate(head)
    deallocate(current)
   end program LinkedList



    subroutine insertItem(pos,item)
     use global
     implicit none 

     type(node) ,pointer ::item,pos

     if(associated(pos%next)) then
     item%next =>pos%next
     pos%next=>item
     end if

  end subroutine insertItem

Intel Fortran usually indicates which line is offending. You should include the **complete** error message and the command which has generated it. — Vladimir F Героям слава, Feb 25 '16 at 12:28
At least item in the subroutine should be `target` and not `pointer` but there will be probably more errors. — Vladimir F Героям слава, Feb 25 '16 at 12:31
1>G:\VS\files\LoopLinkedList\LoopLinkedList\LoopLinkedList.for(34): error #7121: A ptr dummy may only be argument associated with a ptr, and this array element or section does not inherit the POINTER attr from its parent array. [CURRENT]@VladimirF — Arin Immo, Feb 25 '16 at 12:31
There is a pointer array, but there is no array of pointers. You can create an array of a derived type with a pointer component instead. — Vladimir F Героям слава, Feb 25 '16 at 12:41
@ Vladimir F yes, I want to create a pointer array,that is`type(node), pointer::item,head(1000),current(1000)`,and each element in the array as the head to create relevant linkedLists, it seems wrong either . I don't know how to create ab array of derived type In Fortran. So strange syntax of Fortran. — Arin Immo, Feb 25 '16 at 12:48
You can see somethng like [this question](http://stackoverflow.com/q/8900336). If you want a detailed explanation of why your error message comes about, though, I guess someone could. — francescalus, Feb 25 '16 at 12:49
@ Vladimir F .I am confused about Pointer Array and array of pointers,a little hard to understand it for a Chinese.. — Arin Immo, Feb 25 '16 at 12:54
@ francescalus,It may hit the point ,I will try it,Thanks a lot. — Arin Immo, Feb 25 '16 at 13:00
@francescalus oh,my god! it works! so many thanks for your suggestion! — Arin Immo, Feb 25 '16 at 13:39
I think one could still have an array of the base objects, which would be the first object in the list. I managed to compile the code just by changing the subroutine to `type(node) ::pos; type(node) ,target ::item` — Vladimir F Героям слава, Feb 25 '16 at 13:50

Array element does not inherit the POINTER attr from its parent array

0 Answers0