fortran subroutine: array of arbitrary type

Question

I'm trying to write a subroutine to reverse the rows of an array. The following works, but explicitly declares the type of its input arr. Thus I'd need a separate subroutine to do the same thing for an array of type real. Surely there's a way to make it accept an array of arbitrary type - could someone help me with the syntax? Thanks!

SUBROUTINE flipud(arr)

    integer, dimension(:,:), intent(inout) :: arr
    integer, dimension(:,:), allocatable :: tmp
    integer i, j, nrow, ncol, ierr

    nrow = size(arr, 1)
    ncol = size(arr, 2)

    allocate(tmp(nrow, ncol), STAT=ierr)

    tmp(:,:) = arr(nrow:1:-1, :)
    arr = tmp
    deallocate(tmp)

END SUBROUTINE flipud

Answer 1

Fortran does not have the equivalent of C++ templates. You can create an interface with module procedures, as sketched below. The code that is common to both subroutines could be placed in a file that is incorporated using the INCLUDE statement.

module foo
interface fliupud
   module procedure flipud_i,flipud_r
end interface flipud

contains
subroutine flipud_i(arr)
integer, dimension(:,:), intent(inout) :: arr
! body
end subroutine flipud_i
!
subroutine flipud_r(arr)
real, dimension(:,:), intent(inout) :: arr
! body
end subroutine flipud_r
end module foo