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comparison scripts/io/is_valid_file_id.m @ 11142:3450551f591e

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new function, is_valid_file_id
author John W. Eaton <jwe@octave.org>
date Sat, 23 Oct 2010 01:50:14 -0400
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children 461ae8d58cdb
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11141:224c80da37c5 11142:3450551f591e
1 ## Copyright (C) 2010 John W. Eaton
2 ##
3 ## This file is part of Octave.
4 ##
5 ## Octave is free software; you can redistribute it and/or modify it
6 ## under the terms of the GNU General Public License as published by
7 ## the Free Software Foundation; either version 3 of the License, or (at
8 ## your option) any later version.
9 ##
10 ## Octave is distributed in the hope that it will be useful, but
11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 ## General Public License for more details.
14 ##
15 ## You should have received a copy of the GNU General Public License
16 ## along with Octave; see the file COPYING. If not, see
17 ## <http://www.gnu.org/licenses/>.
18
19 ## -*- texinfo -*-
20 ## @deftypefn {Function File} {} is_valid_file_id (@var{fid})
21 ## Return true if @var{fid} refers to an open file.
22 ## @seealso{fopen}
23 ## @end deftypefn
24
25 function retval = is_valid_file_id (fid)
26
27 retval = false;
28
29 if (nargin == 1)
30 try
31 [file, mode, arch] = fopen (fid);
32 retval = ! isempty (file);
33 end_try_catch
34 else
35 print_usage ();
36 endif
37
38 endfunction