allocatable extended derived data type

[wang__shihao]

I am coding a program with allocatable derived datatype like the following code.

my problem is that after allocating test_array using type child, the data is not well allocated. It turns out that the allocated test_array only has integer A, without integer B.

Are there any way to allocate such an array test_array with all data from parent and child data type?

Thanks!

program test
use p_c
call data_allocator
!write(*,*) test_array(2)%B

module p_c
type,abstract,public::parent
integer::A=1
end type parent

type,extends(parent)::child
integer::B=2
end type child

class(parent),allocatable,dimension(:)::test_array
contains

subroutine data_allocator
allocate(child::test_array(5))

end subroutine data_allocator

end module p_c

end program test

[Steven_L_Intel1 · Accepted solution]

It does work, but your program isn't correct in how it sees it. In the commented out WRITE, the compiler uses the "declared type", which is parent, and that doesn't have a B component. You have to do it this way:

[fortran]
module p_c
type,abstract,public::parent
integer::A=1
end type parent

type,extends(parent)::child
integer::B=2
end type child

class(parent),allocatable,dimension(:)::test_array
contains

subroutine data_allocator
allocate(child::test_array(5))

end subroutine data_allocator

end module p_c
program test
use p_c
call data_allocator
select type(test_array)
    type is (child)
    write(*,*) test_array(2)%B
    class default
    write (*,*) "Oops!"
    end select

end program test
[/fortran]

[wang__shihao]

thank you, Steve!

Shihao