FUNCTION dustem_read_chrg,file,silent=silent,help=help

;+
; NAME:
;   dustem_read_chrg
;
; PURPOSE:
;   reads information relating to grain charge from the
;   appropriate .DAT files
;
; CATEGORY:
;    DustEMWrap, Distributed, LowLevel, Initialization
;
; CALLING SEQUENCE:
;   st=dustem_read_chrg(file)
;
; INPUTS:
;    file  : file to be read
;
; OPTIONAL INPUT PARAMETERS:
;    None
;
; OUTPUTS:
;    st   : dustem data structure
;
; OPTIONAL OUTPUT PARAMETERS:
;    None
;
; ACCEPTED KEY-WORDS:
;    help     : writes this help
;
; COMMON BLOCKS:
;    None
;
; SIDE EFFECTS:
;    Files are written
;
; RESTRICTIONS:
;    The DustEM fortran code must be installed
;    The DustEMWrap IDL code must be installed
;
; PROCEDURES AND SUBROUTINES USED:  
;
; EXAMPLES:
;
; MODIFICATION HISTORY:
;    Evolution details on the DustEMWrap gitlab.
;    See http://dustemwrap.irap.omp.eu/ for FAQ and help.  
;-

  IF keyword_set(help) THEN BEGIN
     doc_library,'dustem_read_chrg'
     full_st=0.
     goto,the_end
  ENDIF

  
;CAUTION: the data is read as strings ...

st=''
Nmax=10000L
sts=strarr(Nmax)
openr,unit,file,/get_lun
  
;==read comments
str=''
comments=['']
first_char='#'
Ncomments=0L
WHILE first_char EQ '#' DO BEGIN
  readf,unit,str
  first_char=strmid(str,0,1)
  comments=[comments,str]
  IF first_char EQ '#' THEN Ncomments=Ncomments+1
ENDWHILE

comments=comments[1:*]
IF Ncomments NE 0 THEN comments=comments[0:Ncomments-1]

;stop

;==read data
;last line in previous WHILE loop is first data
tmp = [str]
WHILE NOT EOF(unit) DO BEGIN
  readf, unit, str
  tmp = [tmp, str]
ENDWHILE
;==save and return structure
full_st={file:file,fchrg:tmp,comments:comments}
  
close,unit
free_lun,unit

the_end:

RETURN,full_st
  
END