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In Octave a character string is just a special Array
class.
Consider the example
/* Copyright (C) 2006, 2007 John W. Eaton 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 <http://www.gnu.org/licenses/>. */ #include <octave/oct.h> DEFUN_DLD (stringdemo, args, , "String Demo") { int nargin = args.length(); octave_value_list retval; if (nargin != 1) print_usage (); else { charMatrix ch = args(0).char_matrix_value (); if (! error_state) { if (args(0).is_sq_string ()) retval(1) = octave_value (ch, true); else retval(1) = octave_value (ch, true, '\''); octave_idx_type nr = ch.rows(); for (octave_idx_type i = 0; i < nr / 2; i++) { std::string tmp = ch.row_as_string (i); ch.insert (ch.row_as_string(nr-i-1).c_str(), i, 0); ch.insert (tmp.c_str(), nr-i-1, 0); } retval(0) = octave_value (ch, true); } } return retval; }
An example of the of the use of this function is
s0 = ["First String"; "Second String"]; [s1,s2] = stringdemo (s0) => s1 = Second String First String => s2 = First String Second String typeinfo (s2) => sq_string typeinfo (s1) => string
One additional complication of strings in Octave is the difference
between single quoted and double quoted strings. To find out if an
octave_value
contains a single or double quoted string an example is
if (args(0).is_sq_string ()) octave_stdout << "First argument is a singularly quoted string\n"; else if (args(0).is_dq_string ()) octave_stdout << "First argument is a doubly quoted string\n";
Note however, that both types of strings are represented by the
charNDArray
type, and so when assigning to an
octave_value
, the type of string should be specified. For example
octave_value_list retval; charNDArray c; ... // Create single quoted string retval(1) = octave_value (ch, true, '\''); // Create a double quoted string retval(0) = octave_value (ch, true);