<DIV>Thanks for your help, I modify those params and get right return&nbsp;values now.</DIV>

<DIV>&nbsp;</DIV>

<DIV>As I want to write a function, which can automatically return a rusult, that&nbsp;whether the input raster file&nbsp;has a&nbsp;set of subdataset.</DIV>

<DIV>I use a metadata item of "subdataset", and this value is known from another program&nbsp;but not api doc.</DIV>

<DIV>&nbsp;</DIV>

<DIV>By&nbsp;generally reading the api doc, and as a freshman, I find it hard to get exact value of those const char params and options.</DIV>

<DIV>&nbsp;</DIV>

<DIV>Do you have a&nbsp;good idea?<BR><BR></DIV>

<DIV></DIV><BR><PRE>在2009-10-16&nbsp;01:50:33，"Even&nbsp;Rouault"&nbsp;&lt;even.rouault@mines-paris.org&gt;&nbsp;写道：

&gt;Selon&nbsp;Chaitanya&nbsp;kumar&nbsp;CH&nbsp;&lt;chaitanya.ch@gmail.com&gt;:

&gt;

&gt;Atubar

&gt;

&gt;As&nbsp;Chaintanya&nbsp;says&nbsp;and&nbsp;the&nbsp;doc&nbsp;recommands&nbsp;it,&nbsp;you&nbsp;must&nbsp;use&nbsp;the&nbsp;macro&nbsp;and&nbsp;not

&gt;string&nbsp;values&nbsp;directly.&nbsp;For&nbsp;one&nbsp;good&nbsp;reason&nbsp;:&nbsp;#define&nbsp;ODrCCreateDataSource

&gt;expands&nbsp;to&nbsp;"CreateDataSource"...&nbsp;So&nbsp;"ODrCCreateDataSource"&nbsp;is&nbsp;an&nbsp;invalid&nbsp;input

&gt;for&nbsp;OGRSFDriver::TestCapability().

&gt;

&gt;You're&nbsp;also&nbsp;mentionning&nbsp;functions&nbsp;that&nbsp;take&nbsp;strings&nbsp;as&nbsp;arguments&nbsp;but&nbsp;you&nbsp;don't

&gt;know&nbsp;which&nbsp;values&nbsp;are&nbsp;valid.&nbsp;Could&nbsp;you&nbsp;be&nbsp;more&nbsp;explicit&nbsp;about&nbsp;which&nbsp;functions&nbsp;?

&gt;Generally&nbsp;the&nbsp;doc&nbsp;should&nbsp;make&nbsp;it&nbsp;clear&nbsp;about&nbsp;the&nbsp;expected&nbsp;meaning&nbsp;/&nbsp;accepted

&gt;values.&nbsp;But&nbsp;things&nbsp;can&nbsp;always&nbsp;be&nbsp;improved&nbsp;;-)

&gt;

&gt;Even

&gt;

&gt;&gt;&nbsp;atubar,

&gt;&gt;

&gt;&gt;&nbsp;Here&nbsp;is&nbsp;a&nbsp;sample.

&gt;&gt;&nbsp;http://trac.osgeo.org/gdal/browser/trunk/gdal/apps/ogr2ogr.cpp#L401

&gt;&gt;&nbsp;The&nbsp;preferred&nbsp;#define&nbsp;macro&nbsp;forms&nbsp;are&nbsp;used&nbsp;here.&nbsp;(

&gt;&gt;&nbsp;http://www.gdal.org/ogr/classOGRSFDriver.html#6c37cb7552902cd27cd6d4b904d7c744

&gt;&gt;&nbsp;)

&gt;&gt;

&gt;&gt;&nbsp;As&nbsp;per&nbsp;your&nbsp;problem,&nbsp;perhaps&nbsp;the&nbsp;drivers&nbsp;you&nbsp;tested&nbsp;did&nbsp;indeed&nbsp;not&nbsp;support

&gt;&gt;&nbsp;creation&nbsp;and&nbsp;deletion.&nbsp;Which&nbsp;drivers&nbsp;were&nbsp;they?

&gt;&gt;

&gt;&gt;&nbsp;2009/10/15&nbsp;atubar&nbsp;&lt;atubar@126.com&gt;

&gt;&gt;

&gt;&gt;&nbsp;&gt;&nbsp;Hi,

&gt;&gt;&nbsp;&gt;

&gt;&gt;&nbsp;&gt;&nbsp;I&nbsp;want&nbsp;to&nbsp;take&nbsp;a&nbsp;test&nbsp;about&nbsp;the&nbsp;capability&nbsp;of&nbsp;creation&nbsp;and&nbsp;deletion&nbsp;for

&gt;&gt;&nbsp;&gt;&nbsp;all&nbsp;supported&nbsp;formats&nbsp;of&nbsp;ogr&nbsp;.

&gt;&gt;&nbsp;&gt;

&gt;&gt;&nbsp;&gt;&nbsp;The&nbsp;code&nbsp;like&nbsp;below,&nbsp;&nbsp;The&nbsp;parameter&nbsp;"const&nbsp;char"&nbsp;are&nbsp;copied&nbsp;from&nbsp;api&nbsp;doc.

&gt;&gt;&nbsp;&gt;&nbsp;But&nbsp;all&nbsp;flag&nbsp;return&nbsp;a&nbsp;value&nbsp;of&nbsp;0,&nbsp;why&nbsp;?

&gt;&gt;&nbsp;&gt;

&gt;&gt;&nbsp;&gt;&nbsp;&nbsp;&nbsp;int&nbsp;flag;

&gt;&gt;&nbsp;&gt;

&gt;&gt;&nbsp;&gt;&nbsp;&nbsp;&nbsp;flag=poDriver-&gt;TestCapability("ODrCCreateDataSource");

&gt;&gt;&nbsp;&gt;&nbsp;&nbsp;&nbsp;if(flag==TRUE)

&gt;&gt;&nbsp;&gt;&nbsp;&nbsp;&nbsp;&nbsp;cout&lt;&lt;endl&lt;&lt;"&nbsp;&nbsp;--Supported&nbsp;Creation.&nbsp;"&lt;&lt;endl;

&gt;&gt;&nbsp;&gt;&nbsp;&nbsp;&nbsp;flag=poDriver-&gt;TestCapability("ODrCDeleteDataSource");

&gt;&gt;&nbsp;&gt;&nbsp;&nbsp;&nbsp;if(flag==TRUE)

&gt;&gt;&nbsp;&gt;&nbsp;&nbsp;&nbsp;&nbsp;cout&lt;&lt;endl&lt;&lt;"&nbsp;&nbsp;--Supported&nbsp;Deletion.&nbsp;"&lt;&lt;endl;

&gt;&gt;&nbsp;&gt;

&gt;&gt;&nbsp;&gt;&nbsp;Many&nbsp;funcions&nbsp;need&nbsp;const&nbsp;char&nbsp;*&nbsp;params,&nbsp;is&nbsp;there&nbsp;a&nbsp;list&nbsp;of&nbsp;these&nbsp;values&nbsp;?

&gt;&gt;&nbsp;&gt;

&gt;&gt;&nbsp;&gt;

&gt;&gt;&nbsp;&gt;

&gt;&gt;&nbsp;&gt;

&gt;&gt;&nbsp;&gt;&nbsp;------------------------------

&gt;&gt;&nbsp;&gt;

&gt;&gt;&nbsp;ç½æååå¹´èäº¿èµæé

&gt;ï¼3Då½éµç½æ¸¸ãå¤©ä¸è´°ãï¼åè´¹é¢åç&lt;http://allyes.nie.163.com/main/adfclick?db=afanie&amp;bid=1256,612,23&amp;cid=146,4,1&amp;sid=1353&amp;show=ignore&amp;url=http://tx2.163.com/fab.html&gt;

&gt;&gt;&nbsp;&gt;&nbsp;_______________________________________________

&gt;&gt;&nbsp;&gt;&nbsp;gdal-dev&nbsp;mailing&nbsp;list

&gt;&gt;&nbsp;&gt;&nbsp;gdal-dev@lists.osgeo.org

&gt;&gt;&nbsp;&gt;&nbsp;http://lists.osgeo.org/mailman/listinfo/gdal-dev

&gt;&gt;&nbsp;&gt;

&gt;&gt;

&gt;&gt;

&gt;&gt;

&gt;&gt;&nbsp;--

&gt;&gt;&nbsp;Best&nbsp;regards,

&gt;&gt;&nbsp;Chaitanya&nbsp;kumar&nbsp;CH.

&gt;&gt;

&gt;

&gt;

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