C#调用dll始终报"尝试读取或写入受保护的内存"

[TT_12346333]

以下是我的源代码
[DllImport ("SmGwAPI.dll")]
private static extern int SMGPSendSingle(
int nNeedReply,
int nMsgLevel,
string sServiceID,
int nMsgFormat,
string sFeeType,
string sFeeCode,
string sFixedFee,
string sValidTime,
string sAtTime,
string sSrctermId,
string sChargeTermID,
string sDestTermID,
int nMsgLen,
string sMsgContent,
StringBuilder sMsgID,
ref int nErrorCode,
string sMsgType,
string sReserved);



public void smgpsendsingle(ref MT submit)
{

StringBuilder msgid=new StringBuilder(20);

byte[] bytes = Encoding.GetEncoding(this._encodetype).GetBytes(submit.MsgContent);
submit.MsgLen = bytes.Length;

if (bytes.Length > this._maxsmslength)
{
submit.MsgContent = Encoding.GetEncoding(this._encodetype).GetString(bytes, 0, this._maxsmslength);
submit.MsgLen = this._maxsmslength;
}

int times = 0;
int rt = -1;
lock(object1)
{

while (times < this._mtretry || this._mtretry == 0)
{
rt = SMGPSendSingle(submit.NeedReply,
submit.MsgLevel,
submit.ServiceID,
submit.MsgFormat,
submit.FeeType,
submit.FeeCode,
submit.FixedFee,
submit.ValidTime,
submit.AtTime,
submit.SrcTermID,
submit.ChargeTermID,
submit.DestTermID,
submit.MsgLen,
submit.MsgContent,
msgid,
ref submit.ErrorCode,
submit.MsgType,
submit.Reserved);

哪位大侠搭救一下

[gzxlq]

我原来遇到就是因为数据宽度超过了

[TT_12346333]

StringBuilder我设过256
其他参数我都是传0 不太可能超长，继续等

[真相重于对错]

dll 的c 申明??

[gui0605]

参数类型是什么？

[kongdelu2008]

用import引入DLL

[我在深圳搬砖-Justin]

不用 loack看看

[birdlonger]

估计是你声明的时候参数类型 对应错误..
给下DLL中的函数的定义让大家看下啊?