From help-octave-request at bevo dot che dot wisc dot edu  Fri Mar 20 15:43:19 1998
Subject: About .oct file (2)
From: Shiou-Jhy Ja <jshiouj at radar dot ecen dot okstate dot edu>
To: help-octave at bevo dot che dot wisc dot edu
Date: Fri, 20 Mar 1998 15:41:12 -0600

Hi:
	Thanks for peoples for replying my questions.  But I didn't express my
question clear enough.  What I need is to conver the octave
objects(Matrix, string, ...) to C++ objects(double *, char *,...).

	Because I only have some c++ routines in the library form(no source
available), so I can't modify those source codes to make them accept
octave objects.  Therefor, I need to transform the data which is send
from octave console back to the type that c++ compiler can accept.
For example:

	A function available in tools.a:
	double spline(double *x, double *y, double Ix)

	and I like to call it from octave:
	octave:> vec_Iy = Cspline( vec_x, vec_y, vec_Ix);


> In post "RE: About .oct filt":
>   
>| for matrix, I use a silly way to do it:
>| 
>|    Matrix oct_x=arg(0).matrix_value();
>| 
>|    int n=oct_x.column();  //assume it's a row vector
>| 
>|    double *x=new double[n];
>| 
>|    for (int i=0; i<n; i++)
>|        x[i]=oct_x(0,i);
>| 
>|    then I can call other routin with x
>
>You can extract the data from an Octave Matrix object using
>
>  const double *d = val.matrix_value().data()

If I use the approach above, then the type mismatch happened(ie. const
double* and double*).  

	Another question is about converting octave object, string, to c++
object, char*,  instead of assign a string to octave_value.     
	
>..., you need to use
>
>  arg(0).string_value().c_str()
>
>but that returns `const char *', so you can't use that as the first
>argument to strcpy.  If you are trying to assing a character string to
>an Octave object, just do it:
>
>  octave_value val = "foobar";

So how can I get a 'char *' instead of 'const char*'?

	Thanks for your kindly help.  Programing is not my major,  so please
bear with my such simple questions! 


Puck
jshiouj at radar dot ecen dot okstate dot edu