C / C++ / MFC

CDC ScreenDC;
ScreenDC.Attach(::GetDC(NULL));

CBitmap Capture;
CSize   Dimensions(GetSystemMetrics(SM_CXSCREEN), GetSystemMetrics(SM_CYSCREEN));
Capture.CreateCompatibleBitmap(&ScreenDC, Dimensions.cx, Dimensions.cy);

CDC MemDC;
MemDC.CreateCompatibleDC(&ScreenDC);

CBitmap *OldBitmap = MemDC.SelectObject(&Capture);

MemDC.BitBlt(0, 0, Dimensions.cx, Dimensions.cy, &ScreenDC, 0, 0, SRCCOPY);

MemDC.SelectObject(OldBitmap);
MemDC.DeleteDC();

::ReleaseDC(NULL, ScreenDC.Detach());
//At this point the bitmap 'Capture' should contain an image of the desktop

void CRabbitDlg::OnButton1() 
{
   LockWindowUpdate();
   Sleep( 3000 );
   UnlockWindowUpdate();
}

BYTE pb[]={0x46, 0x4F, 0x4F};
const int SIZE = sizeof(pb)/sizeof(pb[0]);
TCHAR *psz = new TCHAR[2*SIZE+1];
int i;

for (i=0; i<size;> {
  _stprintf(psz+2*i, _T("%02x"), pb[i]);
}
psz[2*i]=_T('\0');

// where pszCharArr is declared as TCHAR *

  DWORD j =0;
  for (i = 0; i < dwSizeOfStrBuf ; i++)
  {
    BYTE b = lpb[i];
    BYTE b0 = (b>>4) & 0x0F;
    BYTE b1 = b & 0x0F;
     if((0<= b0) && (b0 <= 9))
          pszCharArr[j] = _T('0') + b0;
     else
          pszCharArr[j] = _T('A') + (b0 - 10);
     j++;
     if((0<= b1) && (b1 <= 9))
          pszCharArr[j] = _T('0') + b1;
     else
          pszCharArr[j] = _T('A') + (b1 - 10);
     j++;
}
pszCharArr[j] = _T('\0');