Programming Forums > Application Development > C++

rpg_code_master · Aug 18th, 2005, 7:35 PM

Hello

I am interfacing a VB ActiveX DLL with C++ via COM. It compiles and links, but it does not run correctly. I can successfully get the desired interface via CoCreateInstance. When I try though, to pass a Long into one of the VB interfaced functions, I get a 'Cannot read from 0x...' error. Have you any ideas as to why? Maybe a C++ Long != a VB Long�?

Thank you

Scorpions4ever · Aug 18th, 2005, 8:36 PM

On a 32 bit VC++ compiler, VC++ long = VB Long.

The Dark · Aug 19th, 2005, 4:09 AM

Is the VB function parameter passed by reference or passed by value? It may be that you are passing the value of the long and the VB DLL is trying to treat it as an address.

Aug 18th, 2005, 7:35 PM	#1
rpg_code_master Newbie Join Date: Apr 2005 Location: Milton Keynes - England Posts: 9 Rep Power: 0	C++ Long, and Visual Basic Long Hello I am interfacing a VB ActiveX DLL with C++ via COM. It compiles and links, but it does not run correctly. I can successfully get the desired interface via CoCreateInstance. When I try though, to pass a Long into one of the VB interfaced functions, I get a 'Cannot read from 0x...' error. Have you any ideas as to why? Maybe a C++ Long != a VB Long�? Thank you

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Aug 18th, 2005, 8:36 PM	#2
Scorpions4ever Programmer Join Date: Jun 2005 Posts: 86 Rep Power: 4	On a 32 bit VC++ compiler, VC++ long = VB Long.

Aug 19th, 2005, 4:09 AM	#3
The Dark Expert Programmer Join Date: Jun 2005 Posts: 882 Rep Power: 4	Is the VB function parameter passed by reference or passed by value? It may be that you are passing the value of the long and the VB DLL is trying to treat it as an address.

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Programming Forums > Application Development > C++

C++ Long, and Visual Basic Long