效率是否一样
///////////////#1/////
CRect rect(0, 0, 10000, 10000);
UINT nNum = 0;
for (int c = 0; c < rect.Width(); ++c)
nNum += c;
///////////////#2///////
CRect rect(0, 0, 10000, 10000);
UINT nNum = 0;
int nCount = rect.Width();
for (int c = 0; c < nNum; ++c)
nNum += c;