program ch1804a
implicit none
real , pointer :: p1 => null()
real , pointer :: p2 => null()
  allocate(p1)
  p1=21.0
! the value 21.0 is now stored in the memory  
! location that p1 points to
  p2=>p1
  print *,p1
  print *,p2
  p2=p2+1
  print *,p1
  print *,p2
  deallocate(p1)
! this releases the memory and now p1 is disassociated
  print *,p2
end program ch1804a