Calling C DLL from C#

我正试图从c#调用C DLL，但我没有任何乐趣。DLL的文档提供了一个VB的函数声明示例，看起来像;

Declare Function TransGeogPt Lib "c:'DLLS'GDAit.dll" (ByVal sGridFile As String, ByVal lDirection As
Long, ByVal dLat As Double, ByVal dLong As Double, pdLatNew As Double, pdLongNew As Double,
pdLatAcc As Double, pdLongAcc As Double) As Long
Declare Function TransProjPt Lib "c:'DLLS'GDAit.dll" (ByVal sGridFile As String, ByVal lDirection As
Long, ByVal dLat As Double, ByVal dLong As Double, ByVal lZone As Long, pdLatNew As Double,
pdLongNew As Double, pdLatAcc As Double, pdLongAcc As Double) As Long

因此，我做了以下操作;

public class GDAIt
{
    public static string gridFileName = @"C:'Nat84.gsb";
    [DllImport(@"c:'GDAit.dll")]
    public static extern long TransGeogPt(string sGridFile, long lDirection, double dLat, double dLong, ref double pdLatNew, ref double pdLongNew, ref double pdLatAcc, ref double pdLongAcc);
    [DllImport(@"c:'GDAit.dll")]
    public static extern long TransProjPt(string sGridFile, long lDirection, double dLat, double dLong, long lZone, ref double pdLatNew, ref double pdLongNew, ref double pdLatAcc, ref double pdLongAcc);
    public static long CallTransGeogPt(string sGridFile, long lDirection, double dLat, double dLong, ref double pdLatNew, ref double pdLongNew, ref double pdLatAcc, ref double pdLongAcc)
    {
        return TransGeogPt(sGridFile, lDirection, dLat, dLong, ref pdLatNew, ref pdLongNew, ref pdLatAcc, ref pdLongAcc);
    }
    public static long CallTransProjPt(string sGridFile, long lDirection, double dLat, double dLong, long lZone, ref double pdLatNew, ref double pdLongNew, ref double pdLatAcc, ref double pdLongAcc)
    {
        return TransProjPt(sGridFile, lDirection, dLat, dLong, lZone, ref pdLatNew, ref pdLongNew, ref pdLatAcc, ref pdLongAcc);
    }

    public static void Process()
    {
        double latitude = 0.0;
        double longitude = 0.0; 
        double latAcc = 0.0; 
        double longAcc = 0.0;
        long result = 0;
        result = CallTransProjPt(gridFileName,
                                        1,
                                        394980,
                                        7619799,
                                        51,
                                        ref latitude,
                                        ref longitude,
                                        ref latAcc,
                                        ref longAcc);
        Console.WriteLine(string.Format("Result was {0}, Lat: {1}, Long: {2}", result, latitude, longitude));
        int error = Marshal.GetLastWin32Error();
        Console.WriteLine(string.Format("Last error recieved was {0}", error));
    }
}

我仍然没有太多的运气，并尝试了DLLImport语句中的各种其他设置，例如;SetLastError = true, CharSet = CharSet。Auto, CallingConvention = CallingConvention. cdecl)

我从代码得到的输出是;

Result was 4690529317195612196, Lat: 0, Long: 0
Last error recieved was 6

如果我在查看Win32错误的信息是正确的，我认为这是指;ERROR_INVALID_HANDLE句柄无效
6 (0 x6)

我的猜测是有一个问题在文件名作为一个字符串传递或我通过ref传递双精度的方式?然而，我真的不知道，我不知道如何进一步调查这个问题。

有任何想法都非常感谢。

谢谢。