ARCGIS9求面积出错，大家看是怎么回事

<P>错误提示</P>
<P>Executing (CalculateAreas_23): CalculateAreas 农用地投影 G:\shanchu\New_Shapefile.shp<BR>Start Time: Wed Jan 16 22:37:22 2008<BR>Running script CalculateAreas...<BR>Output G:\shanchu\New_Shapefile.shp already exists<BR>Failed to execute (CalculateAreas_23).<BR>End Time: Wed Jan 16 22:37:22 2008 (Elapsed Time: 0.00 secs)</P>

<P 0cm 0cm 0pt">在<FONT face="Times New Roman">Arcgis</FONT>中如何求面积</P>
<P 0cm 0cm 0pt">先打开属性表，在要计算的“字段”上右击<FONT face="Times New Roman">-calculate value--</FONT>弹出对话框（字段计算器）</P>
<P 0cm 0cm 0pt">选中“高级”前的复选框，</P>
<P 0cm 0cm 0pt">这时在<FONT face="Times New Roman">pre-logic</FONT>··<FONT face="Times New Roman">code</FONT>中输入：</P>
<P 0cm 0cm 0pt"><FONT face="Times New Roman">dim d as double</FONT></P>
<P 0cm 0cm 0pt"><FONT face="Times New Roman">dim p as iarea</FONT></P>
<P 0cm 0cm 0pt"><FONT face="Times New Roman">set p=[shape]</FONT></P>
<P 0cm 0cm 0pt"><FONT face="Times New Roman">d=p.area</FONT></P>
<P 0cm 0cm 0pt">然后在<FONT face="Times New Roman">ArEA=</FONT>下输入</P>
<P 0cm 0cm 0pt"><FONT face="Times New Roman">d</FONT></P>
<P 0cm 0cm 0pt">点击“确认”即可<FONT face="Times New Roman">```</FONT></P>
<P 0cm 0cm 0pt">如果要换算为公顷时，在<FONT face="Times New Roman">ArEA=</FONT>下输入</P>
<P 0cm 0cm 0pt"><FONT face="Times New Roman">d/10000</FONT></P>
<P 0cm 0cm 0pt"><p><FONT face="Times New Roman"> </FONT></p></P>
<P 0cm 0cm 0pt">如果要换算为亩时，在<FONT face="Times New Roman">ArEA=</FONT>下输入</P>
<P 0cm 0cm 0pt"><FONT face="Times New Roman">d/10000*15</FONT></P>