I have written a derived type that stores a multidimensional array. The array will be read from a file to an array b. I then want to transfer b to the derived type Space using member a. The advantage for mvalloc is not having to allocate two large arrays which might create memory problems.
When I compile the code I am getting the error
Call Move_Alloc (b, t% a)
1
Error: 'from' argument of 'move_alloc' intrinsic
at (1) must be ALLOCATABLE
The type definition and relevant subroutine follows
Type, Public :: Space
Character (Len=65) :: nm
Real, Allocatable :: a(:,:,:)
Contains
Procedure :: mvalloc => space_mvalloc
End Type Space
Subroutine space_mvalloc (t, b)
Class (Space), Intent (InOut) :: t
Real, Intent (InOut) :: b(:,:,:)
Call Move_Alloc (b, t% a)
End Subroutine space_mvalloc
As the error message says, the arguments to move_alloc must be allocatable. That's both of them. from is the first, and this must be allocatable for the allocation to move from it.
You have
Subroutine space_mvalloc (t, b)
Class (SField), Intent (InOut) :: t
Real, Intent (InOut) :: b(:,:,:)
Call Move_Alloc (b, t% a)
End Subroutine space_mvalloc
b here is not allocatable. You should add that attribute, and ensure that the actual argument passed in is allocatable.
After the call to move_alloc b, and the corresponding actual argument, will be unallocated.