module plink_module
implicit none
  type plink
    character (len=6) :: patient_number = ' '
    character (len=20) :: ward = ' '
    type (plink), pointer :: next => null()
  end type plink
end module plink_module

program ch22_patients
use plink_module
  implicit none
  character :: more = 'N'
  type (plink), pointer :: root, current

! allocate space for 1st item in list

  allocate (root)
  print *, 'input Patient number:'
  read '(A)', root%patient_number
  print *, 'input hospital ward for this patient:'
  read '(A)', root%ward

! allocate space for 2nd item in list (will be a blank item at end)

  allocate (root%next)
  print *, 'another patient? (Y/N)'
  read '(A)', more
  current => root

! current points to beginning of list

  do while (more=='Y' .or. more=='y')

! current points to next item in list

    current => current%next
    print *, 'input Patient number:'
    read '(A)', current%patient_number
    print *, 'input hospital ward for this patient:'
    read '(A)', current%ward

! allocate space for next item in list (will be a blank item at end)

    allocate (current%next)
    print *, 'another patient? (Y/N)'
    read '(A)', more
  end do

! Print out patient numbers and wards

  print 100
100 format (1x,'Patient number',3x,'ward')
  current => root
  do
    print 200, current%patient_number, current%ward
200 format (5x,a,7x,a)

! current points to next item in list

    current => current%next
    if ( .not. associated(current%next)) exit
  end do
end program ch22_patients