1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
|
########################################################################
##
## Copyright (C) 2010-2024 The Octave Project Developers
##
## See the file COPYRIGHT.md in the top-level directory of this
## distribution or <https://octave.org/copyright/>.
##
## This file is part of Octave.
##
## Octave is free software: you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## Octave is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with Octave; see the file COPYING. If not, see
## <https://www.gnu.org/licenses/>.
##
########################################################################
## -*- texinfo -*-
## @deftypefn {} {@var{tf} =} is_valid_file_id (@var{fid})
## Return true if @var{fid} refers to an open file.
## @seealso{freport, fopen}
## @end deftypefn
function tf = is_valid_file_id (fid)
if (nargin < 1)
print_usage ();
endif
tf = false;
try
if (isscalar (fid))
[file, mode, arch] = fopen (fid);
tf = ! isempty (file);
endif
end_try_catch
endfunction
%!assert (is_valid_file_id (stdout))
%!assert (! is_valid_file_id ([1,2;3,4]))
%!assert (! is_valid_file_id ("not_a_file_id"))
%!assert (! is_valid_file_id (-1))
%!assert (! is_valid_file_id (pi))
%!test <*65543>
%! unwind_protect
%! fid = tmpfile ();
%! assert (is_valid_file_id (fid));
%! unwind_protect_cleanup
%! fclose (fid);
%! end_unwind_protect
## Test input validation
%!error <Invalid call> is_valid_file_id ()
|
