access a c -dll function problem

Question

Hi @ all and thanks for reading: i have got some problems to access a c - (dll)function from c# this is the prototype: status theFunction ( PVOID pvArg1PVOID pvArg2 DWORD dwFlags ); pvArg1 Meaning depends on dwFlags pvArg2 Meaning depends on dwFlags dwFlags Determines format of returned information one way to use the function is DWORD i=0; char* Buffer[16]; / status = theFunction ((PVOID)i Buffer FLAG1|FLAG2); the function stores a value in the char-Buffer under visual c++ the function works perfectly this way. now i dont know how to marshal the first arg (PVOID)i .... i tried it with IntPtr ref i ect. but without success :-( the second problem: how can i marshal char* Buffer? ([MarshalAs(UnmanagedType.LPTStr)] string? [MarshalAs(UnmanagedType.LPTStr)] StringBuffer??) thanks a lot Landy

bilnaad · Answer

whoops public static extern status theFunction(void* pvArg1 void*pvArg2 ulong dwFlags); should be public unsafe static extern status theFunction(void* pvArg1 void*pvArg2 ulong dwFlags); ^_^

bilnaad · Answer

you could just use unsafe code and use a void* variable. public static extern status theFunction(void* pvArg1 void*pvArg2 ulong dwFlags); unsafe { ulong i = 0; char[] buffer = new char[16]; fixed(char* bufferPtr = buffer) { someVariable = theFunction((void*)i (void*)bufferPtr FLAG1|FLAG2); } } Maybe something like this will work. I hope it helps you find a solution.