[geos-devel] Exceptions and CAPI

[Olivier Bedel]

hrz at geodata.soton.ac.uk wrote:

>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
>  
>
Thanks Homme,

You were right. By initialising GEOS with initGEOS, it solves the problem.

Best regards,

Olivier.