#! /bin/csh -f
#
#  get a two digit yy code from the user; insure validity; return code
#  as exit condition
#
while(1)
  echo "input_yy:  enter 2 digit shot-year (btw 00 and 99):"
  set yyi = $<
  switch ($yyi)
    case [0-9]:
      set yy = "0$yyi"
      breaksw
    default:
      set yy = "$yyi"
      breaksw
  endsw
  yy_valid $yy
  if ( $status) then
    exit $yy
  endif
end
