;+
; @file_comments
; give back the liste of variables included in a NetCDF file
;
; @categories 
; NetCDF
;
; @param input {in}{required}{type=salar string or long integer} 
; the name of the file or its Id (defined by a previus call to
; ncdf_open or ncdf_create)
; Note that if input corresponds to the file name, ncdf_listvars will
; open and close the file automatically.
;
; @returns
; a vector string containing the name of the variables
;
; @examples
;
;   IDL> varnames = ncdf_listvars('toto.nc')
;
;   or
;
;   IDL> i=ncdf_open('toto.nc')
;   IDL> varnames = ncdf_listvars(id)
; 
; @history
;
;
; @version
; $Id$
;
;-
FUNCTION ncdf_listvars, input
;
  compile_opt idl2, strictarrsubs
;
  IF size(input, /type) EQ 7 THEN ncid = ncdf_open(input) ELSE ncid = input
  
  n = (ncdf_inquire(ncid)).nvars
  names = strarr(n)
  for i = 0, n-1 do names[i] = (ncdf_varinq(ncid, i)).name
  
  IF size(input, /type) EQ 7 THEN ncdf_close, ncid

  return, names
  
END