iterator problem in oct-file

[matthias . bergmeister]

Hello,
I have a strange problem accessing structure
elements in an oct-file. Please have a look at the example below which
runs perfectly with Octave 2.1.73 under cygwin but not with Octave under
2.1.73 under Linux. Please let me know, if you are willing to help but
need further information.

First,  I create a structure, which
I use as test data, in a script file:
*******************************************************************************************************************
structure1.a =4.23;
structure1.b =4;
structure1.c ="testString 1";


structure2.a =2.76;
structure2.b =5;
structure2.c ="testString 2";

structure3.a =3.88;
structure3.b =6;
structure3.c ="testString 3";

testArray(1)=structure1;
testArray(2)=structure2;
testArray(3)=structure3;

Then I call the following oct-file:
//***************************************************************************************************************************
#include <string>
#include <octave/oct.h> 
#include <octave/ov-struct.h>


DEFUN_DLD (conversionExample, prhs,
nlhs ,  "Reproduces an Error which does not occur when cygwin
is used")
{
  
   double a;
   int b;
   std::string c;
   octave_value tmp;
   Octave_map::iterator p1;

      if ( !prhs(0).is_map()
)          {error("First input argument must
be of type struct."); return octave_value(0);}
  
   p1 = prhs(0).map_value().seek("a");
   tmp =  prhs(0).map_value().contents(p1)(1);
   a = tmp.double_value();
   octave_stdout <<
"a is " << a << std::endl;
  
   p1 = prhs(0).map_value().seek("b");
   tmp =  prhs(0).map_value().contents(p1)(2);
   b = tmp.int_value();
   octave_stdout <<
"b is " << b << std::endl;

   p1 = prhs(0).map_value().seek("c");
   tmp =  prhs(0).map_value().contents(p1)(2);
   c = tmp.string_value().data();
   octave_stdout <<
"c is " << c << std::endl;
   return octave_value(0);

}
Letting this oct-file run with testArray
as an argument, octave correctly returns the following under cygwin:
octave:2>conversionExample(testArray)
a is 2.76
b is 6
c is testString3
ans = 0

under linux I get different results.
All of them indicate the "seek"-command does not return iterators
which point to the correct field. e.g.:
octave:3> conversionExample(testArray)
a is 5
error: invalid conversion from string
to real scalar
error: octave_base_value::int_value
(): wrong type argument 'string'
b is 0
warning: implicit conversion fom scalar
to string
c is

Regards
Matthias