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Old September 5th, 2005, 11:54 AM
gjc gjc is offline
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Default Using DLLs in VB 6

I whish to use a DLL I have created in VC++ so I have put the DLL in my system32 directory and declared the function I whish to use as follows:

Private Declare Function testFunc Lib _
"CalibrationDLL" (num As Integer) As Integer

the prototype in the DLL is:

extern "C" {
    int DLLDIR testFunc(int Num);

I then call the function in the code like this:

testResult = testFunc(1)

However, this throws and a run time error of:

Bad DLL calling convention.

What have I missed?


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Old September 6th, 2005, 01:17 PM
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The problem is name decoration, that is you have to tell the compiler that the names of the methods should be left "as is", something like:

__declspec(dllexport) int testFunc(int Num)

and because you want to pass parameters to the methods, do not forget to generate the .def file.
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Old September 7th, 2005, 03:47 AM
gjc gjc is offline
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That's what the DLLDIR macro does. the problem was that I needed to add__stdcall in front of the the function within the DLL.

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