Calling from C# to C function which accept a struct array allocated by caller
- by lifey
I have the following C struct
struct XYZ
{
void *a;
char fn[MAX_FN];
unsigned long l;
unsigned long o;
};
And I want to call the following function from C#:
extern "C" int func(int handle, int *numEntries, XYZ *xyzTbl);
Where xyzTbl is an array of XYZ of size numEntires which is allocated by the caller
I have defined the following C# struct:
[System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential, CharSet = System.Runtime.InteropServices.CharSet.Ansi)]
public struct XYZ
{
public System.IntPtr rva;
[System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst = 128)]
public string fn;
public uint l;
public uint o;
}
and a method:
[System.Runtime.InteropServices.DllImport(@"xyzdll.dll",
CallingConvention = CallingConvention.Cdecl)]
public static extern Int32 func(Int32 handle, ref Int32 numntries,
[MarshalAs(UnmanagedType.LPArray)] XYZ[] arr);
Then I try to call the function :
XYZ xyz = new XYZ[numEntries];
for (...) xyz[i] = new XYZ();
func(handle,numEntries,xyz);
Of course it does not work. Can someone shed light on what I am doing wrong ?
