Need help calling a DLL with PTR parm

[John Kovacich]

I need to call a DLL with a prototype which looks like this:

'BOOL DLLENTRY SomeDLL(GLOBALHANDLE FAR *SomeList)
DECLARE FUNCTION SomeDLL LIB "SOME.DLL" (BYVAL SomeList AS DWORD PTR) AS LONG

The dword points to a string array. How do I define this, and how do I define an array to use this pointer?

DIM SomeArray(10) AS STRING ' The list
DIM SomeList as DWORD PTR ' Doesn't this point to a DWORD?
SomeList = VARPTR(SomeArray()) ' To get the string segment?



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Thanks,

John Kovacich

[Tom Hanlin]

By the looks of the C function above your DECLARE, assuming that's the
same function, SomeList is a pointer to a GLOBALHANDLE (which
is a HANDLE, which is a DWORD). Literally, the translation to
BYVAL SomeList AS DWORD PTR is correct. However, it is useful
to remember that C has no way of passing anything BYREF except by
using pointers. In this case, what you want is more probably:

DECLARE FUNCTION SomeDLL ALIAS "SomeDLL" LIB "SOME.DLL" (BYREF SomeList AS DWORD) AS LONG

Now, SomeList here is really a GLOBALHANDLE, which is very much
not a string array. Of course, in C or in PowerBASIC, it is common enough
to define a parameter as one thing for convenience, and then override it
at some other point. It would be fairly odd to coerce a GLOBALHANDLE into
a string array, though, I think. It seems like a step or two must be
missing here. Can you provide more detail?

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Tom Hanlin
PowerBASIC Staff