win7; vc6;在视类CPP文件头部添加宏定义；
void CDfdemoView::OnDraw(CDC* pDC){CDfdemoDoc* pDoc = GetDocument();ASSERT_VALID(pDoc);// TODO: add draw code for native data hereCString str1, str2;float r = 1.0;float area = PI * r * r; str1.Format("%f", area);pDC->TextOut(20,20,str1);int a = 2* T1; //宏替换后变成 int a = 2*3+4int b = 2* T2; //宏替换后变成 int a = 2*(3+4)str1.Format("%d", a);str2.Format("%d", b);pDC->TextOut(20,50,str1);pDC->TextOut(20,80,str2);//#undef PI//float area2 = PI * r * r;//error: ‘PI’ was not declared in this scopeint sum= MAX(5,7) + MIN(5,7);str1.Format("%d", sum);pDC->TextOut(20,110,str1);}
使用PI、T1、T2的输出；
如果在使用PI之前，执行 #undef ，则出错；
使用MIN和MAX宏的输出；
