C++ object call from LabVIEW

[christophe74]

Hello,

I have been using LabVIEW for nearly 10 years but I have to admit I am a little stuck.

I have to use several VC++ DLLs from LabVIEW 2009.

I have no choice than using those DLLs as the code is very large and there is no time to revert back to LabVIEW only.

I have found a good article about calling C++ using a C wrapper at http://labviewwiki.org/DLL/shared_library

I was wondering if someone had done something where instead of calling a double it would be an object.

Any help would be welcome.

Many Thanks,

Christophe

[Aristos Queue]

  On 1/12/2010 at 7:28 PM, christophe74 said:

Hello,

I have been using LabVIEW for nearly 10 years but I have to admit I am a little stuck.

I have to use several VC++ DLLs from LabVIEW 2009.

I have no choice than using those DLLs as the code is very large and there is no time to revert back to LabVIEW only.

I have found a good article about calling C++ using a C wrapper at http://labviewwiki.o.../shared_library

I was wondering if someone had done something where instead of calling a double it would be an object.

Any help would be welcome.

Many Thanks,

Christophe

The only DLL calls I've had to make to C++ all involved a C interface where I just needed to pass the pointer to the class (which LV can easily hold onto in a uInt32 or a uInt64 as long as LV isn't expected to access the data of the object directly). I'm sure there is a solution if the interface is actually a C++ exported function, but I don't know what it is. This may be a question better posted on NI.com/forums pages. The AEs there get questions about DLL calls all the time and may have a ready answer for you. No promises, but I'd suggest trying it.

[Rolf Kalbermatter]

  On 1/18/2010 at 4:53 PM, Aristos Queue said:

The only DLL calls I've had to make to C++ all involved a C interface where I just needed to pass the pointer to the class (which LV can easily hold onto in a uInt32 or a uInt64 as long as LV isn't expected to access the data of the object directly). I'm sure there is a solution if the interface is actually a C++ exported function, but I don't know what it is. This may be a question better posted on NI.com/forums pages. The AEs there get questions about DLL calls all the time and may have a ready answer for you. No promises, but I'd suggest trying it.

Calling C++ functions gets nasty if you have several variants of the same function with different parameters since you have to figure out which decorated function name you want to access for a particular parameter version. And the decoration while logically corresponding to the parameter list, is anything but easy to decipher (and varies between C compilers too).

Accessing methods and member elements of objects will only be doable with C wrapper interfaces though.