问题描述

c#调用C++的DLL时调用失败

本人C#小白。老大要求用C#调用C++的DLL.
C++的我写出来了，可以调用成功.
#include
#include
void main(){
HMODULE hModule = ::LoadLibrary(_T(""C:CT_InfoTerm.dll""));
typedef LONG (WINAPI pDLLProc)(intcharintintintchar*int);
pDLLProc dllfunc;
int iPort = 0;
char cExtendPort[1] = {'9'};
int iBaudRate = 9600;
int iVoiceType = 0;
int iTimeOut = 30;
char cPin[256];
memset(cPin NULL sizeof(cPin));
dllfunc = (pDLLProc)
::GetProcAddress((HMODULE)hModuleCT_ReadPin"");
int iReturn;
if (dllfunc != NULL){
iReturn = dllfunc(iPort cExtendPort iBaudRate iVoiceType iTimeOut cPin sizeof(cPin));
}
}

现在改为C#的
[DllImport(""CT_InfoTerm.dll"" EntryPoint = ""CT_ClosePinPad"" CallingConvention=CallingConvention.Cdecl)]
public unsafe static extern int CT_ReadPin(int iPortNo char extendPort int iBaudRate int iVoiceType int iTimeOut StringBuilder Pin int iPinSize);

        public unsafe void CT_ReadPin(WebCommand command)     {        int nRet = -3;//打开串口失败(默认)        if (_canRead)        {            int iPortNo = 0;            char extendPort = '9';            int iBaudRate = 9600;            int iVoiceType = Convert.ToInt16(command.Parameter);            int iTimeOut =30;           //var Pin=new byte[100];            StringBuilder Pin = new StringBuilder(1024);           // string Pin = new string(Convert.ToChar("" "") 256);           // char Pin = new char();            int iPinSize =256;            nRet = Centerm.CT_ReadPin(iPortNoextendPortiBaudRateiVoiceTypeiTimeOutPiniPinSize);            checkresult(command nRet);        }     }            pin是返回值            注释的地方是我尝试的方法，并不报任何错误，但是C#的调用不成功，可能是pin这个参数有问题.            各位大神能不能提供一些思路，供我参考一下，多谢

解决方案

pin是StringBuilder，要转化成String类型啊

解决方案二：
C#调用VC的DLL时AfxGetApp失败的解决方法
C#调用C++ dll时CallingConvention调用约定详解
关于在C#中调用C++ DLL 时的参数传递