"GeRmIc" <Ge****@discussions.microsoft.com> wrote in message
news:5C**********************************@microsof t.com...
[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Ansi)]
public struct L_Germplasm
{
public long gdate;
public long gid;
public long glocn; ....etc., around 9 long fields
}
I have to pass an array of such structures to my C program in one hit
(instance).
Ok, there are several way's to marshal such simple array of struct .
Here's one of them:
//C# prog.
[StructLayout(LayoutKind.Sequential)]
struct S
{
internal int a;
internal int b;
internal int c;
internal int d;
}
class Tester
{
[DllImport("nativeStrucArr.dll")]
private static extern void func_c( S[] ao, int len);
static void Main()
{
int elem = 10;
S[] IntArray = new S[elem];
for (int s = 0;s < elem ; s++)
{
IntArray[s].a = elem - s;
IntArray[s].b = elem - s;
IntArray[s].c = elem - s;
IntArray[s].d = elem - s;
}
// Pass array and number of elements, IntArray is pinned for the duration of
the call only!
func_c( IntArray, IntArray.Length);
}
}
//C program....
struct S
{
int a;
int b;
int c;
int d;
};
// take pointer to void for the array pointer
extern "C" {
__declspec(dllexport) void __stdcall func_c (void * pas, int len);
}
void __stdcall func_c (void * pas, int len)
{
int ret = 0;
S *sa = new S[len]; // allocate array of struct in native heap
S *s = static_cast<S*>(pas); // cast array * to struct *
// copy array of struct elements to new array (native memory)
for (int n = 0; n < len; n++)
{
sa[n].a = (s + n)->a;
sa[n].b = (s + n)->b;
sa[n].c = (s + n)->c;
sa[n].d = (s + n)->d;
}
// Use array when done
// Dump to console for demo
for (int n = 0; n < len; n++)
{
printf_s("Cont %d\n", sa[n].a);
printf_s("Cont %d\n", sa[n].b);
printf_s("Cont %d\n", sa[n].c);
printf_s("Cont %d\n", sa[n].d);
}
}
OR
How do can I hold that array of structures in C# Library itself and then
pass one such structure each time the C DLL contacts the C# Library?
Not sure what you mean with OR.
What exactly do you mean with contacts the C# library? How do I
hold and pass the address of the ArrayList or HashTable between the C DLL
and
C# Library?
Any suggestions/help to any of the above two questions would be greatly
appreciated.
But it seems like you are looking for something which isn't possible, you
cannot take the address of a managed object and use it as such in unmanaged
code.
That's the whole point of marshaling, a C program has no idea what an
Hashtable is or looks like, so you have to convert the data members to
something that C can understand and use, and that is what marshaling is
about.
Willy.
