在vc中使用静态变量的问题++ MFC

Question

mydialog 类声明。 …………………… 我的工作是创建一个带有按钮和文本框的窗口，当我第一次单击该按钮时，将创建一个线程，该线程将在所选端口上读取，对于按钮上文本框中的后续数据，单击它只会写入端口而不是创建线程进行读取。

#include "resource.h"

class mydialog : public CDialog
{
    DECLARE_DYNAMIC(mydialog)

public:
    mydialog(CWnd* pParent = NULL);   // standard constructor
    virtual ~mydialog();
    static HANDLE hSerial4;
    static int loop_count;

// Dialog Data
    enum { IDD = IDD_DIALOG1 };

protected:
    virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support

    DECLARE_MESSAGE_MAP()
public:
    CString m_name;
    afx_msg void OnBnClickedButton1();
    BOOL OnInitDialog();
    static UINT read_data(LPVOID hSerial);
//  void read_data(HANDLE);
    CString select_port;
};

cpreparationapp.cpp ........................

#include "stdafx.h"
#include "mydialog.h"

class CPreparationApp : public CWinApp
{
public:
    BOOL InitInstance();
};


BOOL CPreparationApp::InitInstance()
{

    mydialog Dlg;
    Dlg.DoModal();
    m_pMainWnd = &Dlg;
    return TRUE;
}

CPreparationApp theApp;

mydialog.cpp ……………………

#include "stdafx.h"
#include "mydialog.h"
#include <windows.h>
#include <process.h> 



// mydialog dialog

IMPLEMENT_DYNAMIC(mydialog, CDialog)

mydialog::mydialog(CWnd* pParent /*=NULL*/)
    : CDialog(mydialog::IDD, pParent)
    , m_name(_T(""))
    , select_port(_T(""))
{

}

mydialog::~mydialog()
{
}

void mydialog::DoDataExchange(CDataExchange* pDX)
{
    CDialog::DoDataExchange(pDX);
    DDX_Text(pDX, IDC_EDIT1, m_name);
    DDX_CBString(pDX, IDC_COMBO1, select_port);
}


BEGIN_MESSAGE_MAP(mydialog, CDialog)
    ON_BN_CLICKED(IDC_BUTTON1, &mydialog::OnBnClickedButton1)
END_MESSAGE_MAP()


// mydialog message handlers
void mydialog::OnBnClickedButton1()
{
    CEdit* abc=(CEdit*)GetDlgItem(IDC_EDIT1);
    LPTSTR xyz123=new TCHAR[50];
    CString text;
    int k=abc->GetWindowTextA(xyz123,20);
    CComboBox * pCombo=(CComboBox *)GetDlgItem(IDC_COMBO1);
    int item = pCombo->GetCurSel();
    if(item != CB_ERR)
    {
        pCombo->GetLBText(item,text);
    }
    TRACE("%s\n",text); 
    loop_count++;
    HANDLE hSerial;
    if(loop_count==1)
    {
    hSerial = CreateFile(text,
    GENERIC_WRITE | GENERIC_READ,
    FILE_SHARE_READ | FILE_SHARE_WRITE,
    0,
    OPEN_EXISTING,
    FILE_ATTRIBUTE_NORMAL,
    0);

    if(hSerial==INVALID_HANDLE_VALUE)
    {
        if(GetLastError()==ERROR_FILE_NOT_FOUND)
        {
            TRACE("serial port does not exist for writing\n");
        //serial port does not exist. Inform user.
        }
            TRACE("some other error,serial port does not exist for writing\n");
        //some other error occurred. Inform user.
    }

    DCB dcbSerialParams = {0};

    dcbSerialParams.DCBlength=sizeof(dcbSerialParams);

    if (!GetCommState(hSerial, &dcbSerialParams)) 
    {
                    TRACE("error getting state for writing\n");
    //error getting state
    }

    dcbSerialParams.BaudRate=CBR_19200;
    dcbSerialParams.ByteSize=8;
    dcbSerialParams.StopBits=ONESTOPBIT;
    dcbSerialParams.Parity=NOPARITY;

    if(!SetCommState(hSerial, &dcbSerialParams))
    {
                    TRACE("error setting state for writing\n");
    //error setting serial port state
    }
    COMMTIMEOUTS timeouts={0};

    timeouts.ReadIntervalTimeout=50;
    timeouts.ReadTotalTimeoutConstant=50;
    timeouts.ReadTotalTimeoutMultiplier=10;

    timeouts.WriteTotalTimeoutConstant=50;
    timeouts.WriteTotalTimeoutMultiplier=10;

    if(!SetCommTimeouts(hSerial, &timeouts))
    {
                    TRACE("some error occured for writing\n");
        //error occureed. Inform user
    }
    mydialog::hSerial4=hSerial;
    }
    int n=100;
    char szBuff1[100];
    int m=0;
    while(m<100 && xyz123[m]!='\0')
    {
        szBuff1[m]=xyz123[m];
        m++;
    }
    szBuff1[m]='\0';
    DWORD dwByteswrote = 0;

    if(!WriteFile(mydialog::hSerial4, szBuff1, n, &dwByteswrote, NULL))
    {
                    TRACE("error writing \n");
    }           
    TRACE("%d\n",dwByteswrote);
//  mydialog Dlg1;
    if(loop_count==1)
    {
    CWinThread *m_pThread;
    m_pThread=AfxBeginThread(read_data,(LPVOID)hSerial);
    }

}

 UINT mydialog::read_data(LPVOID hSerial5)
{
    HANDLE hSerial1=(HANDLE)hSerial5;
    int n=100;
    char szBuff[100];
    DWORD dwBytesRead = 0;

    if(!ReadFile(hSerial1, szBuff, n, &dwBytesRead, NULL))
    {
                    TRACE("error reading \n");
        //error occurred. Report to user.
    }

    TRACE("%s\n",szBuff);
//  TRACE("%d\n",dwBytesRead);
    CloseHandle(hSerial1);

    return 1;
}



BOOL mydialog::OnInitDialog()
{
//  BOOL x;
    mydialog dialog2;
    HANDLE hSerial3;
    CString temp,temp1;
    int n=0;
    CComboBox * pCombo=(CComboBox *)GetDlgItem(IDC_COMBO1);
    pCombo->AddString("SAMPLE1");
    pCombo->AddString("SAMPLE2");
    for(n=0;n<9;n++)
    {
        temp1.Format("%d",n);
        temp="COM"+temp1;
        hSerial3 = CreateFile(temp,
        GENERIC_WRITE | GENERIC_READ,
        FILE_SHARE_READ | FILE_SHARE_WRITE,
        0,
        OPEN_EXISTING,
        FILE_ATTRIBUTE_NORMAL,
        0);
        if(hSerial3==INVALID_HANDLE_VALUE)
        {

            TRACE("port not available\n");
        }
        else
        {   
            pCombo->AddString(temp);
            CloseHandle(hSerial3);
            TRACE("port available\n");
        }

    }       
//  x=dialog2.check_open_port();
    return CDialog::OnInitDialog();
}

Answer 1

您已在类中声明了静态成员但尚未定义它们，因此您会收到链接器错误。

在类体之外提供定义

HANDLE mydialog::hSerial;
int mydialog::loop_count;