Unmanaged struct

[aCiD2]

I am getting the following compile error:

E:\Computer Work\C#\Projects\SharpVorbis\Class1.cs(103): Cannot take the address or size of a variable of a managed type ('SharpVorbis.Ogg_H.oggpack_buffer')

Add line 103 is:
public static extern void oggpack_writetrunc(oggpack_buffer *b, long bits);

The definition of oggpack_buffer is:
unsafe struct oggpack_buffer
{
long endbyte;
int endbit;

string buffer;
string ptr;
long storage;
}
(The unsafe is there because i was trying to make it unmanaged

[pareshgh]

public static extern void oggpack_writetrunc(oggpack_buffer *b, long bits);

if you know the size here you can allocate size and then get value,
otherwise use ref keyword
like

public static extern void oggpack_writetrunc(ref oggpack_buffer b, long bits);

regards
Paresh.