LabVIEW
what is LV c code representation of NULL string
dgholstein wrote:
> I know that through .so/.dll code the representation of any string is
> a structure of the length followed by the characters, I allocate a
> long blank string in the LV code and copy over my strings in the
> so/.dll and that works fine. How do I return a LV NULL string?
As long as LabVIEW is not supporting 64 bit platforms a NULL pointer is
really just a 32 bit integer with the value 0.
So if you want to call a dll/so function which allows for a NULL pointer
as parameter, you configure that parameter to be a signed or unsigned 32
bit integer and wire the value 0 to its input.
As to the LabVIEW string itself if you call a DLL it is usually better
to use a C string type instead of the native LabVIEW handle. Once you
use a LabVIEW handle t
hat DLL really is difficult to use in other
environments than LabVIEW.
Rolf Kalbermatter
> I know that through .so/.dll code the representation of any string is
> a structure of the length followed by the characters, I allocate a
> long blank string in the LV code and copy over my strings in the
> so/.dll and that works fine. How do I return a LV NULL string?
As long as LabVIEW is not supporting 64 bit platforms a NULL pointer is
really just a 32 bit integer with the value 0.
So if you want to call a dll/so function which allows for a NULL pointer
as parameter, you configure that parameter to be a signed or unsigned 32
bit integer and wire the value 0 to its input.
As to the LabVIEW string itself if you call a DLL it is usually better
to use a C string type instead of the native LabVIEW handle. Once you
use a LabVIEW handle t
hat DLL really is difficult to use in other
environments than LabVIEW.
Rolf Kalbermatter
