EVC技巧

1   为对话框添加菜单，。变量须设置为全局

     //先创建一个Command_Bar
     HWND hwndCB = CommandBar_Create (AfxGetInstanceHandle(), m_hWnd, 1);

     ///再插入菜单:
     CommandBar_InsertMenubar (hwndCB, AfxGetInstanceHandle(),IDR_MENU1, 0);

2   int与string的相互转化int to string :

     int index=0;

     CString str;

     str.Format(_T("%d"),index);// str 为 0

     str.Format(_T("%02d"),index); // str 为 00

     string to int :
     CString str = _T("00");
     int index;
     swscanf(str,_T("%d"),&index);
     Cstring to char *
     CString   str   =   _T("CString");  
     char   *pBuffer   =   NULL;  
     pBuffer   =   new   char[str.GetLength()+1];  
     ZeroMemory(pBuffer,   str.GetLength()+1);  
   
     int   iLen   =   str.GetLength();  
     for(int   i   =   0;   i   <   iLen;   i++)  
     pBuffer[i]   =   str[i];  
     pBuffer[i]   ='/0';  
   
     pDC->ExtTextOut(0,   0,   0,   NULL,   pBuffer,   NULL);  
     delete[]   pBuffer;  
   
     ------------------  
    eVC++4.0上已经测试通过

    上述方法针对中文就有问题，根源在   Unicode   上。类似下面的代码更好：    
    #include   <atlconv.h>     
    USES_CONVERSION;  
    CString   str="Cstring";  
    char   *p;  
    p=(char*)W2A((LPCTSTR)str); 

3.EVC实现WIN CE下截屏并且保存到文件

     // this function create a bmp file to save the current screen;
     // supported eVC++ 4.0 (wince 4.0) and vc++ 6.0 , test pass;
    void CSnapDlg::OnScreenSave(const char *filename)
   {
      HDC hScrDC, hMemDC;        
       int width, height;

     //the pointer will save all pixel point's color value
     BYTE *lpBitmapBits = NULL;
       
    //creates a device context for the screen device
    hScrDC = CreateDC(_T("DISPLAY"), NULL, NULL, NULL);

    //get the screen point size
    width = GetDeviceCaps(hScrDC, HORZRES);
    height = GetDeviceCaps(hScrDC, VERTRES);

    //creates a memory device context (DC) compatible with the screen device(hScrDC)
    hMemDC = CreateCompatibleDC(hScrDC);

//initialise the struct BITMAPINFO for the bimap infomation，
//in order to use the function CreateDIBSection
// on wince os, each pixel stored by 24 bits(biBitCount=24)
//and no compressing(biCompression=0)
    BITMAPINFO RGB24BitsBITMAPINFO;
    ZeroMemory(&RGB24BitsBITMAPINFO, sizeof(BITMAPINFO));
    RGB24BitsBITMAPINFO.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    RGB24BitsBITMAPINFO.bmiHeader.biWidth = width;
    RGB24BitsBITMAPINFO.bmiHeader.biHeight = height;
    RGB24BitsBITMAPINFO.bmiHeader.biPlanes = 1;
    RGB24BitsBITMAPINFO.bmiHeader.biBitCount = 24;
  
//use the function CreateDIBSection and SelectObject
//in order to get the bimap pointer : lpBitmapBits
    HBITMAP directBmp = CreateDIBSection(hMemDC, (BITMAPINFO*)&RGB24BitsBITMAPINFO,
       DIB_RGB_COLORS, (void **)&lpBitmapBits, NULL, 0);
HGDIOBJ previousObject = SelectObject(hMemDC, directBmp);

// copy the screen dc to the memory dc
BitBlt(hMemDC, 0, 0, width, height, hScrDC, 0, 0, SRCCOPY);

//if you only want to get the every pixel color value,
//you can begin here and the following part of this function will be unuseful;
//the following part is in order to write file;

//bimap file header in order to write bmp file
BITMAPFILEHEADER bmBITMAPFILEHEADER;
ZeroMemory(&bmBITMAPFILEHEADER, sizeof(BITMAPFILEHEADER));
bmBITMAPFILEHEADER.bfType = 0x4d42; //bmp
    bmBITMAPFILEHEADER.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);
    bmBITMAPFILEHEADER.bfSize = bmBITMAPFILEHEADER.bfOffBits + ((width*height)*3); ///3=(24 / 8)

//write into file
FILE *mStream = NULL;
if((mStream = fopen(filename, "wb")))
{
//write bitmap file header
fwrite(&bmBITMAPFILEHEADER, sizeof(BITMAPFILEHEADER), 1, mStream);
//write bitmap info
fwrite(&(RGB24BitsBITMAPINFO.bmiHeader), sizeof(BITMAPINFOHEADER), 1, mStream);
//write bitmap pixels data
fwrite(lpBitmapBits, 3*width*height, 1, mStream);
   //close file
fclose(mStream);
}

//delete
DeleteObject(hMemDC);
DeleteObject(hScrDC);
DeleteObject(directBmp);
DeleteObject(previousObject);
}

 

5 还回 系统时间
    long   Milliseconds=GetTickCount();

    CString   log;  
    SYSTEMTIME   CurTime;  
    GetLocalTime(&CurTime);  
    log.Format(_T("%d-%d-%d,%d:%d:%d,"),    
   CurTime.wYear,   CurTime.wMonth,   CurTime.wDay,  
   CurTime.wHour,   CurTime.wMinute,   CurTime.wSecond   ); 

 

 

6 读文本
    CFileDialog   cfd(TRUE,NULL,NULL,OFN_HIDEREADONLY|OFN_OVERWRITEPROMPT,_T("文本文件(*.txt)|*.txt|所有文     件           (*.*)|*.*||"));  
   
 if(cfd.DoModal()==IDCANCEL)  
 return;  
   
 CFile   cf;  
 CFileException   cfe;  
 //TCHAR   *tc;  
 char   *tc;  
   
  if(cf.Open(cfd.GetPathName(),CFile::modeRead,&cfe)==FALSE)  
 {  
  AfxMessageBox("不能读取文件："+cfd.GetPathName());  
  return;  
  }  
   
   tc=new   char[cf.GetLength()];  
   cf.Read(tc,cf.GetLength());  
   CString   str1=tc;  
   delete   []   tc;  
   
   cf.Close();  
   
  AfxMessageBox(str1); 

7.char *_gcvt( double value, int digits, char *buffer )函数使用问题
功能: 将浮点型数据转换为字符串
digits不能超过16,否则计算精度将出问题.
例如:
double preNum=9.7;
double nextNum=1;
double dblResult=preNum+nextNum;
CString dispText;
dispText=_gcvt(dblResult,20,charBuffer);

理论上dispText为10.7,但实际结果为10.6999999999999999
如果将最后一句改为:
dispText=_gcvt(dblResult,16,charBuffer);
则结果正常.
由此推测,digits参数应该在16以下