From bug-octave-request at bevo dot che dot wisc dot edu  Thu Mar 12 17:22:21 1998
Subject: String arguments to dynamically linked functions
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Markus Svensen <svensen at cns dot mpg dot de>
Cc: bug-octave at bevo dot che dot wisc dot edu
Date: Thu, 12 Mar 1998 17:22:18 -0600 (CST)

On 12-Mar-1998, Markus Svensen <svensen at cns dot mpg dot de> wrote:

: I try to pass a string constant to a dynamically linked C++ function, 
: to be used as a filename. Unfortunately, it seems as if under certain 
: circumstances, this string constant get muddled up somewhere on the 
: way. 
: 
: Repeat-By:
: ---------
: 
: To illustrate the problem I've written another (much smaller) function: 
: 
: #include <octave/oct.h>
: #include <stdio.h>
: 
: DEFUN_DLD (dummy, args, ,
:   "The `dummy'.")
: {
:   octave_value_list retval;
: 
:   /* extract filename from argument list */
:   string fname = args(0).string_value();
: 
:   fprintf(stderr, "Filename: %s\n",((char*) fname.data()));

I think this is the problem.  If you want to extract a NUL-terminated
string from a C++ string object, I think you need to use the
string::c_str() method, not string::data().

Thanks,

jwe