I want to pass a byte[] to a method takes a IntPtr Parameter in C#, is that possible and how?
Not sure about getting an IntPtr to an array, but you can copy the data for use with unmanaged code by using Mashal.Copy:
IntPtr unmanagedPointer = Marshal.AllocHGlobal(bytes.Length);
Marshal.Copy(bytes, 0, unmanagedPointer, bytes.Length);
// Call unmanaged code
Marshal.FreeHGlobal(unmanagedPointer);
Alternatively you could declare a struct with one property and then use Marshal.PtrToStructure, but that would still require allocating unmanaged memory.
Edit: Also, as Tyalis pointed out, you can also use fixed if unsafe code is an option for you
Another way,
GCHandle pinnedArray = GCHandle.Alloc(byteArray, GCHandleType.Pinned);
IntPtr pointer = pinnedArray.AddrOfPinnedObject();
// Do your stuff...
pinnedArray.Free();