[geos-devel] Exceptions and CAPI

[hrz at geodata.soton.ac.uk]

On Mon, Nov 27, 2006 at 05:29:54PM +0000, Olivier Bedel wrote:
> Hi all members of the list,
> 
> I try to handle exception with the CAPI. I use the  GEOSGeomFromWKT 
> function and I want to avoid segmentation fault when a wrong wkt string 
> is given as a parameter. Reading the comments in geos_c.h, I expected 
> this function return a NULL pointer when an exception was raised, but 
> strangely, it seems that he seg fault happens in the function call. So I 
> get no return values and I can't handle exceptions.
> 
> Here is a simple example of what I want to do:
> /****************************/
>  GEOSGeometry *g;
>  g = GEOSGeomFromWKT("POLYGON(0.0 0.0, 1.0 1.0, 2.0 2.0, 0.0 0.0))");
>  if (g==NULL)
>    fprintf(stderr,"g is not a valid geometry\n");
> /****************************/
> 
> Do I miss something ?

Have you initialised GEOS using the initGEOS function? If not, when
geos tries to return an error (as in the above code), it will segfault
as it tries to access a pointer to an error reporting function but
finds NULL instead. This error reporting function is set using
initGEOS. Have a look in capi/geostest.c for an example of how to go
about it.

Kind regards,

Homme