Unhandled exception in XXX.exe(XXX.dll) oxC0000005:Access Violation

[qq_24532765]

各位大神帮帮忙啊！！！！
想用QT 调用vc++创建的MFC Regular dll ,在编写dll时执行到n1500controller.cpp的如下语句
m_nProtocol = nProtocol;
m_nCom = nCom;
m_nControllerID= ControllerID;
时报错：
Unhandled exception in QTtest.exe(N1500USB.DLL):
0xC0000005:Access Violation.
代码如下：
（1）
//n1500controller.h : Declaration of the n1500controller

#ifndef __N1500CONTROLLER_H__
#define __N1500CONTROLLER_H__

#include "resource.h" // main symbols
#include "SerialPort.h"
#include <afxtempl.h>

class n1500controller
{
public:
n1500controller();
virtual ~n1500controller();
bool OpenGstCom(unsigned char nCom, unsigned char ControllerID, unsigned char nProtocol);
bool UpDevice(unsigned char nControllerID, unsigned char nLoop, unsigned char nAddress);


private:
CString DevideHexChar(char HexChar);
bool IsReplied(int nResultBytes, DWORD nTimeout/*,int chEnd*/);//chEnd=-1
bool DataVerify(int nStart, int nEnd);

protected:
CSerialPort m_SerialPort;
unsigned char m_nProtocol;
unsigned char m_nCom;
unsigned char m_nControllerID;
bool m_bGstComOpened;

};

#endif // __N1500CONTROLLER_H__
（2）
// n1500controller.cpp: implementation of the n1500controller class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "N1500USB.h"
#include "n1500controller.h"
#include <assert.h>
#include <afxtempl.h>

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////
n1500controller::n1500controller()
{
m_nProtocol=NULL;
m_nCom=NULL;
m_nControllerID=NULL;
m_bGstComOpened=false;
}
n1500controller::~n1500controller()
{

}

CString n1500controller::DevideHexChar(char HexChar)
{
CString result=_T("");
int temp=(HexChar&0xF0)>>4;
if(temp<10)
result+=(temp+'0');
else
result+=(temp+'A'-10);
temp=HexChar&0x0F;
if(temp<10)
result+=(temp+'0');
else
result+=(temp+'A'-10);
return result;
}

bool n1500controller::IsReplied(int nResultBytes, DWORD nTimeout/*,int chEnd*/)//chEnd=-1
{
//等待应答
if(m_SerialPort.ReceiveChar(nResultBytes))
return true;
else
return false;
}
bool n1500controller::DataVerify(int nStart, int nEnd)
{
unsigned char Sum = 0;
for (int i=nStart;i<nEnd;i++)
{
//Sum += m_SerialPort.m_chInputArray.GetAt(i);
}

//if (Sum == m_SerialPort.m_chInputArray.GetAt(nEnd))//和校验，等于校验位。
return true;
// else
// return false;
}
/************************* openGstCom **********************/
bool n1500controller::OpenGstCom(unsigned char nCom, unsigned char ControllerID, unsigned char nProtocol)
{
AFX_MANAGE_STATE(AfxGetStaticModuleState())

m_nProtocol = nProtocol;
m_nCom = nCom;
m_nControllerID= ControllerID;

//参数合法性检查
int nBaud=19200;
int nBuffer = 1024;
char chParity='N';
if (nProtocol!=230)
return false;

/*if(m_bGstComOpened)
m_SerialPort.CloseCom();*/

if (!m_SerialPort.InitPort(nCom,nBaud,chParity,8,1,EV_RXCHAR,nBuffer))
return false;
else
{
m_bGstComOpened = true;
return true;
}
}

[oyljerry]

查看一下出错的时候的函数调用堆栈，具体那个参数为空指针了

[赵4老师]

崩溃的时候在弹出的对话框按相应按钮进入调试，按Alt+7键查看Call Stack即“调用堆栈”里面从上到下列出的对应从里层到外层的函数调用历史。双击某一行可将光标定位到此次调用的源代码或汇编指令处，看不懂时双击下一行，直到能看懂为止。

[qq_24532765]

@赵4老师 按照你的指示做了 如下： n1500controller::OpenGstCom(int 4, int 1, int 230) line 68 + 6 bytes QTTEST! 00401802() QTTEST! 00401a26() QTTEST! 00401b06() QTCORED4! 6a20611c() QTCORED4! 6a216ab8() QTGUID4! 69580b38() QTGUID4! 692ee953() QTGUID4! 692ee8d1() QTGUID4! 692efd7d() QTGUID4! 68fb6ad8() QTGUID4! 692efc08() QTGUID4! 6938e9e2() QTGUID4! 68f6bd88() QTGUID4! 68f69fd1() QTCORED4! 6a201664() QTGUID4! 695e8182() QTGUID4! 68f687e0() QTGUID4! 68fd3637() QTGUID4! 68fce482() 754962fa() 75496d3a() 754977c4() 7549788a() QTCORED4! 6a225e76() QTGUID4! 68fccf40() QTCORED4! 6a1ff672() QTCORED4! 6a1ff79a() QTCORED4! 6a201c94() QTGUID4! 68f69324() QTTEST! 00401400() QTTEST! 00401f32() QTTEST! 00401c58() QTTEST! 0040124b() QTTEST! 004012b8() KERNEL32! 751f336a() NTDLL! 770c9902() NTDLL! 770c98d5() 感觉还是不知所措

[赵4老师]

看不懂时双击下一行，直到能看懂为止。