开发AE的小提示(C#)

<P>开发时写下列语句竟然出错</P>
<P>   ESRI.ArcGIS.Geometry.IPoint pt = new ESRI.ArcGIS.Geometry.PointClass();<BR>   pt.X += 30;</P>
<P>一开始莫名其秒啊!!</P>

<P>后来发现只要改成如下就OK了：</P>
<P>pt.X = pt.X + 30;</P>
<P>哈哈，应该是 += 操作符的原因了吧!希望大家注意!</P>

<P>好像还是不对啊!</P>
<P>pt.X只可以赋值，不可取值!</P>

<P>double d = pt.X;失败</P>
<P>提示：the operation was attempted on an empty geometry.</P>
<P>pt.X = 30;成功</P>

<P>Points may be constructed using <a href="ms-help://ESRI.ArcGIS/esriGeometry/html/IPoint_PutCoords.htm" target="_blank" >PutCoords</A>, individually setting the X and Y properties, or using the <a href="ms-help://ESRI.ArcGIS/esriGeometry/html/IConstructPoint.htm" target="_blank" >IConstructPoint</A> interface.</P>
<P>必须用PutCoords构造才可以</P>

<P>这么麻烦啊!不习惯!</P>

<P>坏习惯</P>
<P>要不得</P>

恩