C＃/ C ++传递结构获得访问冲突异常

早上好，我正准备实现pos设备。本机api是C ++库，我必须在C＃项目中使用。我已经导入了几乎所有必需的功能（可以正常工作），但是其中有一个我还是无法做到。

这是C ++库中的函数：

__declspec(dllexport) void setHost(char* id, Host* host, char* trx, char* flag);

这是在C ++库中声明的结构：

typedef struct {
   int hostConnectionType;
   char ipAddress[15 + 1];
   int tcpPort;
   int hostTransportProtocol;
   char gtId[5 + 1];
   char gprsAPN[64 + 1];
   char gprsUserName[15 + 1];
   char gprsPassword[8 + 1];
   int tlsCertificateId;
   char personalizationId[10 + 1];
   int gtIndex;
} Host;

这是C ++演示项目中的用法示例：

Host test_host;
test_host.hostConnectionType = 3;
test_host.hostTransportProtocol = 2;
test_host.gtIndex = 9;
strcpy(test_host.ipAddress, "199.188.177.166");
test_host.tcpPort = 54321;
strcpy(test_host.gtId, "12345");
test_host.tlsCertificateId = 21985;
strcpy(test_host.personalizationId, "001");
MobilePosAdapter_dll("00000123", &test_host, "0000000001", "1000");

我在C＃项目中所做的是声明Host结构：

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct Host
{
    public int hostConnectionType;

    public int hostTransportProtocol;

    public int tcpPort;

    public int tlsCertificateId;

    public int gtIndex;

    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)]
    public string ipAddress;

    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 6)]
    public string gtId;

    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 65)]
    public string gprsAPN;

    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)]
    public string gprsUserName;

    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 9)]
    public string gprsPassword;

    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 11)]
    public string personalizationId;
}

然后，声明函数，属性和符号：

[UnmanagedFunctionPointer(CallingConvention.Cdecl, CharSet = CharSet.Ansi)]
private delegate void cdecl__setHost([MarshalAs(UnmanagedType.LPStr)] string id, Host Host, [MarshalAs(UnmanagedType.LPStr)] string trx, [MarshalAs(UnmanagedType.LPStr)] string flags);

private static cdecl__setHost _setHost = (cdecl__setHost)Marshal.GetDelegateForFunctionPointer(NativeMethods.GetProcAddress(DllPtr, "setHost"), typeof(cdecl__setHost));

最后测试一下：

Host host = new Host()
{
    gtId = 12345,
    gtIndex = 0,
    hostConnectionType = 3,
    hostTransportProtocol = 2,
    ipAddress = "199.188.177.166",
    personalizationId = "001",
    tcpPort = 54321,
    tlsCertificateId = 21985
};

_setHost("00000123", host, "0000000001", "1000");

我有一个System.AccessViolationException。

我怎么了

这是整个API中唯一具有结构作为参数的函数。其他函数具有返回值的结构，它们都可以正常工作。