function read_fileidx, filename
openr, unit, filename, /get_lun
fileidx=0
readf, unit, fileidx
free_lun, unit
return, fileidx
end

pro write_fileidx, filename, fileidx
openw, unit, filename, /get_lun
printf, unit, fileidx
free_lun, unit
end

pro write_arr, filename, outarr
openw, unit, filename, /get_lun
printf, unit, outarr
free_lun, unit
end