跪求SelectObject 与CDC 之间的问题解决方案

Question

CDC *m_pDC;
COLORREF ColorValue=RGB(255,255,255);
CRect rect=CRect(50,50,200,200);
CBrush newBrush;
CBrush *oldBrush;
newBrush.CreateSolidBrush(ColorValue);
oldBrush=m_pDC->SelectObject(&newBrush);

m_pDC->Rectangle(rect);
m_pDC->DrawEdge(rect,EDGE_SUNKEN,BF_RECT);
m_pDC->SelectObject(oldBrush);

调试结果： oldBrush=m_pDC->SelectObject(&newBrush);总是出错   句柄为NULL

Answer 1

CDC *m_pDC;，这个m_pDC只指向哪个DC的？你这么写是是声明一个CDC的对象而已，实例化呢？