class UIRect:public RECT
{
public:

    UIRect(LONG leftT = 0, LONG topT = 0, LONG rightT = 0, LONG bottomT = 0)
    {
        left = leftT;
        top = topT;
        right = rightT;
        bottom = bottomT;
    }

    int GetWidth() const 
    {
        return right - left;
    }

    int GetHeight() const
    {
        return bottom - top;
    }


};

void DrawRect(const UIRect& rect)
{
    rect.GetWidth();
}

//只有函數(shù)右邊帶了const，才能被const對象使用，否則報(bào)編譯錯(cuò)誤，error C2662: 'UIRect::GetWidth' : cannot convert 'this' pointer from 'const UIRect' to 'UIRect &'