how to capture the screen

void CaptureImage(void)
{
    HDC hDC;
 
    // First get the Device Context of the desktop
    hDC = GetDC(NULL);

    // Now get the screen size
    SIZE size;
    size.cx = GetSystemMetrics(SM_CXSCREEN);
    size.cy = GetSystemMetrics(SM_CYSCREEN);

    // Now do a BitBlt
    HDC hMemDC = CreateCompatibleDC(hDC);
    HBITMAP hBitmap = CreateCompatibleBitmap(hDC, size.cx, size.cy);
    if (hBitmap) {
         HBITMAP hOldBmp = (HBITMAP) SelectObject(hMemDC, hBitmap);
        BitBlt(hMemDC, 0, 0, size.cx, size.cy, hDC, 0, 0, SRCCOPY);
        SelectObject(hMemDC, hOldBmp);
        DeleteDC(hMemDC);        
        // hBitmap is now a handle to the screen capture. 
        // Do what you want with it here, before deleting it below.
        DeleteObject(hBitmap);
    }
    ReleaseDC(NULL, hDC);
}