c# - how to add namespace using XmlWriter in xml document -

hi have save file in xfdf file in c# using xmlwriter class;

using (var fs = file.open("d://abc.xfdf", filemode.create)) {     try     {         var doc = xmlwriter.create(fs);         doc.writestartelement("highlights");         foreach (var h in highlights)         {             doc.writestartelement("highlight");             doc.writeelementstring("id", h.id);             doc.writeendelement();         }         doc.writeendelement();         doc.flush();     } } 

but not able save in xfdf file. getting problem adding

<xfdf xmlns="http://ns.adobe.com/xfdf/" xml:space="preserve"> 

your link doesn't explain problem is, i'll take sample bit of xml there , walk through creating it. principles can applied whichever elements you're trying create.

<xfdf xmlns="http://ns.adobe.com/xfdf/" xml:space="preserve">     <f href="document.pdf"/>     <fields>         <field name="street">             <value>345 park ave.</value>         </field>             </fields> </xfdf>  

so, while can xmlwriter directly, not idea - it's low level , result not nice read or write. example, code take create outer element , first child. notice how have careful match writing start , end of elements:

writer.writestartelement("xfdf", "http://ns.adobe.com/xfdf/"); writer.writeattributestring("space", "http://www.w3.org/xml/1998/namespace", "preserve"); writer.writestartelement("f", "http://ns.adobe.com/xfdf/"); writer.writeattributestring("href", "document.pdf"); writer.writeendelement(); writer.writeendelement(); 

alternatively, can use higher level, cleaner linq xml api declaratively create xml:

xnamespace ns = "http://ns.adobe.com/xfdf/";  var doc = new xdocument(     new xelement(ns + "xfdf",         new xattribute(xnamespace.xml + "space", "preserve"),         new xelement(ns + "f",             new xattribute("href", "document.pdf")             ),         new xelement(ns + "fields",             new xelement(ns + "field",                 new xattribute("name", "street"),                 new xelement(ns + "value",                     "345 park ave."                     )                 )             )         )     );  doc.save(@"d:\abc.xdfd"); 

you can use api add elements sequence in variety of different ways, such as:

var element = new xelement(ns + "highlights");  foreach (var h in highlights) {     element.add(new xelement(ns + "highlight", h.id)); } 

or:

var element = new xelement(ns + "highlights",     highlights.select(h => new xelement(ns + "highlight", h.id))     ); 

as ever, google friend. there lots of examples on how use linq xml.