module link_module
implicit none
type rlink
real :: n
type (rlink), pointer :: next=>null()
end type rlink

type ilink
integer:: n
type (ilink), pointer :: next=>null()
end type ilink

interface read_data
   module procedure read_real
   module procedure read_integer
end interface

contains
subroutine read_real(x,n)
implicit none
type (rlink), pointer :: root, current
integer :: i = 0
integer, intent(out):: n
integer :: io_stat_number = 0
real, allocatable, dimension (:), intent(out) :: x
character(len=40):: fname

  print *,'file containing real numbers?'
  read '(A)',fname
  open(unit=1,file=fname,status='old')  
  allocate (root)
! read in 1st number from file
  read (unit=1,fmt=*,iostat=io_stat_number) root%n
  if( io_stat_number == 0)then  ! not end of file
    i = i + 1
    allocate (root%next)
  end if
  current => root
! read in remaining numbers (1 per line) 
  do while (associated(current%next))
    current => current%next
    read (unit=1,fmt=*,iostat=io_stat_number) current%n
    if (io_stat_number == 0) then
      i = i + 1
      allocate (current%next)
    end if
  end do
  n = i
  allocate (x(1:n))
  i = 1
  current => root
  do while (associated(current%next))
    x(i) = current%n
    i = i + 1
    current => current%next
  end do
  close (unit=1)
 
end subroutine read_real

subroutine read_integer(x,n)
implicit none
type (ilink), pointer :: root, current
integer :: i = 0
integer, intent(out):: n
integer :: io_stat_number = 0
integer, allocatable, dimension (:), intent(out) :: x
character(len=40):: fname

  print *,'file containing integer numbers?'
  read '(A)',fname
  open(unit=1,file=fname,status='old')  
  allocate (root)
! read in 1st number from file
  read (unit=1,fmt=*,iostat=io_stat_number) root%n
  if( io_stat_number == 0)then  ! not end of file
    i = i + 1
    allocate (root%next)
  end if
  current => root
! read in remaining numbers (1 per line) 
  do while (associated(current%next))
    current => current%next
    read (unit=1,fmt=*,iostat=io_stat_number) current%n
    if (io_stat_number == 0) then
      i = i + 1
      allocate (current%next)
    end if
  end do
  n = i
  allocate (x(1:n))
  i = 1
  current => root
  do while (associated(current%next))
    x(i) = current%n
    i = i + 1
    current => current%next
  end do
  close (unit=1)
  
end subroutine read_integer

end module link_module


program ch2202c    !ch2202a updated to fortran 95
use link_module
implicit none
real,    allocatable, dimension(:):: rx
integer, allocatable, dimension(:):: ix
integer:: i,n
   call read_data(rx,n)
   print*,n,' real data values:'
   do i=1,n
      print*,rx(i)
   end do

   call read_data(ix,n)
   print *,n,' integer data values:'
   do i=1,n
      print*,ix(i)
   end do

end program ch2202c