program main

!*****************************************************************************80
!
!! caesar_test() tests caesar().
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    04 September 2021
!
!  Author:
!
!    John Burkardt
!
  implicit none

  integer k
  character ( len = 80 ) s1
  character ( len = 80 ) s2
  character ( len = 80 ) s3

  call timestamp ( )
  write ( *, '(a)' ) ''
  write ( *, '(a)' ) 'caesar_test():'
  write ( *, '(a)' ) '  Fortran90 version.'
  write ( *, '(a)' ) '  Test caesar().'

  write ( *, '(a)' ) ''
  write ( *, '(a)' ) '  call S_TO_CAESAR ( S1, K, S2 ), varying K.'
  write ( *, '(a)' ) ''
  write ( *, '(a)' ) '   K  ---------------S1--------------  ---------------S2--------------'
  write ( *, '(a)' ) ''
  do k = -5, 5
    s1 = 'A man, a plan, a canal: Panama!'
    call s_to_caesar ( s1, k, s2 )
    write ( *, '(2x,i2,2x,a31,2x,a31)' ) k, s1, s2
  end do

  write ( *, '(a)' ) ''
  write ( *, '(a)' ) '  call S_TO_CAESAR ( S1,  K, S2 ).'
  write ( *, '(a)' ) '  call S_TO_CAESAR ( S2, -K, S3 )'
  write ( *, '(a)' ) ''
  write ( *, '(a)' ) '   K  ------------S1----------  ------------S2----------  ------------S3----------'
  write ( *, '(a)' ) ''
  do k = -5, 5
    s1 = 'The key is under the mat'
    call s_to_caesar ( s1, k, s2 )
    call s_to_caesar ( s2, -k, s3 )
    write ( *, '(2x,i2,2x,a24,2x,a24,2x,a24)' ) k, s1, s2, s3
  end do
!
!  Terminate.
!
  write ( *, '(a)' ) ''
  write ( *, '(a)' ) 'caesar_test():'
  write ( *, '(a)' ) '  Normal end of execution.'
  write ( *, '(a)' ) ''
  call timestamp ( )

  stop 0
end
subroutine timestamp ( )

!*****************************************************************************80
!
!! timestamp() prints the current YMDHMS date as a time stamp.
!
!  Example:
!
!    31 May 2001   9:45:54.872 AM
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    04 September 2021
!
!  Author:
!
!    John Burkardt
!
  implicit none

  character ( len = 8 ) ampm
  integer d
  integer h
  integer m
  integer mm
  character ( len = 9 ), parameter, dimension(12) :: month = (/ &
    'January  ', 'February ', 'March    ', 'April    ', &
    'May      ', 'June     ', 'July     ', 'August   ', &
    'September', 'October  ', 'November ', 'December ' /)
  integer n
  integer s
  integer values(8)
  integer y

  call date_and_time ( values = values )

  y = values(1)
  m = values(2)
  d = values(3)
  h = values(5)
  n = values(6)
  s = values(7)
  mm = values(8)

  if ( h < 12 ) then
    ampm = 'AM'
  else if ( h == 12 ) then
    if ( n == 0 .and. s == 0 ) then
      ampm = 'Noon'
    else
      ampm = 'PM'
    end if
  else
    h = h - 12
    if ( h < 12 ) then
      ampm = 'PM'
    else if ( h == 12 ) then
      if ( n == 0 .and. s == 0 ) then
        ampm = 'Midnight'
      else
        ampm = 'AM'
      end if
    end if
  end if

  write ( *, '(i2.2,1x,a,1x,i4,2x,i2,a1,i2.2,a1,i2.2,a1,i3.3,1x,a)' ) &
    d, trim ( month(m) ), y, h, ':', n, ':', s, '.', mm, trim ( ampm )

  return
end