關於C++可視化編程的問題（畫圖）

int a=0,b=0;

while(a<50,b<50)

{

pDC->Ellipse(a,b,100-a,100-b);//同心圓

a+=10;

b+=10;

}

}

圓心在（50，50）所以最多只能畫5個，多了就出邊界了，沒意義

2：三個圖形

CPen cp; //建立畫筆對象

cp.CreatePen(PS_SOLID,3,RGB(255,0,0)); //建立畫筆

CPen* pOldPen=pDC->SelectObject(&cp); //調用畫筆

pDC->MoveTo(100,100);

pDC->LineTo(400,100);

pDC->LineTo(250,200);

pDC->LineTo(100,100);

pDC->SelectObject(pOldPen);

cp.DeleteObject();

cp.CreatePen(PS_DASH,1,RGB(255,255,255));

pOldPen=pDC->SelectObject(&cp);

pDC->MoveTo(500,200);

pDC->LineTo(800,200);

pDC->LineTo(650,100);

pDC->LineTo(500,200);

pDC->SelectObject(pOldPen);

cp.DeleteObject();

CBrush bh(RGB(0,0,255));

CBrush* pbh=(CBrush*)pDC->SelectObject(&bh);

pDC->Ellipse(300,200,500,400);

pDC->SelectObject(bh);

bh.DeleteObject();

cp.CreatePen(PS_SOLID,1,RGB(255,255,255));

pOldPen=pDC->SelectObject(&cp);

pDC->Ellipse(300,200,500,400);

pDC->SelectObject(pOldPen);

cp.DeleteObject();

發現寫註釋太麻煩了，應該看得懂的吧，語句都很簡單