Fortran code to generate linked-list by pointer.

linked_list_by_pointer.f95

!****************************************************
! 整数値を格納する連結リスト
! : pointer を使用する
!
! date          name            version
! 2017.05.17    mk-mode.com     1.00 新規作成
!
! Copyright(C) 2017 mk-mode.com All Rights Reserved.
!****************************************************
!
program linked_list
  implicit none
  type node
    type (node), pointer :: next_node
    integer value
  end type node
  integer num
  type (node), pointer :: first_node, new_node, p

  nullify (first_node)

  do
    print *, '0 か正の整数を入力してください（負の整数で終了）:'
    read *, num
    if (num < 0) exit

    allocate (new_node)
    new_node%next_node => first_node
    new_node%value = num
    first_node => new_node
  end do

  p => first_node
  print *, "================================"
  do while (associated(p))
    print *, p%value
    p => p%next_node
  end do
end program linked_list