how to pass file reference to c

[jerryvdk]

Hi,

I want to pass file reference pointer to a dll written in visual c++. How can i do that?

[rolfk]

What do you want to do with that reference in your C code? if you want to access it using OS File IO functions you have to be very careful! You should not mix LabVIEW nodes and OS platforms calls together. It's either one or the other.

If you can guarantee that what you want to do is configure the Call Library Node (CLN) parameter to Adapt To Type. Then right click on the CLN and select "Create C Source Header" or something to that meaning. Save the resulting file to disk. Open it and copy the function prototype into your C/C++ file. There should be a parameter typed LVRefnum *. Now you can use the LabVIEW manager C function MgErr FRefNumToFD(LVRefNum refNum, File *fdp);

You need to link your DLL with labview.lib in the cintools directory in order to be able to call the FRefNumToFD() function. The value in the fdp reference is the platform specific file handle, so for Windows this is a HANDLE.