#include <iostream>
using namespace std;
void CScreenShotDlg::OnPaint()
{
// device context for painting
CPaintDC dc(this);
// Get the window handle of calculator application.
HWND hWnd = ::FindWindow( 0, _T( "Calculator" ));
// Take screenshot.
PrintWindow( hWnd,
dc.GetSafeHdc(),
0 );
}
С плюсами толком не знаком.