c# - How to Update XML File in Windows Form -

i'm trying figure out how can go updating xml file. know how read , write, no idea how update existing record.

my xml file looks like:

<?xml version="1.0" standalone="yes"?>       <categories>        <category>         <categoryid>1</categoryid>         <categoryname>ayourvedic</categoryname>        </category>       <category>       <categoryid>2</categoryid>       <categoryname>daily needs</categoryname>      </category>      <category>       <categoryid>3</categoryid>       <categoryname>clothes</categoryname>      </category>      <category>       <categoryid>4</categoryid>       <categoryname>shops</categoryname>      </category>      <category>      <categoryid>5</categoryid>      <categoryname>daily use product</categoryname>      </category>    </categories> 

and how i'm writing file:

   private void btnupdate_click(object sender, eventargs e)     {         xmldocument xdoc = new xmldocument();         string path = "xmldata.xml";         xelement xelement;         xelement = new xelement("category");          xelement element = new xelement(             "category",             new xattribute("categoryid", categoryid),             new xattribute("categoryname", categoryname)              );         xelement.add(element);         xelement.save("path");     } 

but code not working please 1 can give idea or solution.

using system.xml following code shall help:

    static void main(string[] args)     {         string inputfile = @"d:\temp\cat.xml";          xmldocument xmldoc = new xmldocument();         xmldoc.load(inputfile);         xmlnode root = xmldoc.documentelement;          //method 1         xmlelement category = xmldoc.createelement("category");         xmlelement catid = xmldoc.createelement("categoryid");         xmlelement catname = xmldoc.createelement("categoryname");          catid.innertext = "6";         catname.innertext = "the newly added category";          category.appendchild(catid);         category.appendchild(catname);         root.appendchild(category);          //method 2         xmlelement category2 = xmldoc.createelement("category");         string catdata = string.format("<categoryid>{0}</categoryid><categoryname>{1}</categoryname>", "7", "adding data innerxml");          category2.innerxml = catdata;         root.appendchild(category2);          xmldoc.save(inputfile);     } 

for further reading refer xmldocument , xmlnode

using system.linq.xml following shall help:

static void main(string[] args)     {         string inputfile = @"d:\temp\cat.xml";          xdocument xmldoc = xdocument.load(inputfile);         xelement root = xmldoc.root;          root.add(new xelement("category", new xelement("categoryid", "8"), new xelement("categoryname", "added linqxml")));          xmldoc.save(inputfile);     } 

also can refer this answer.

edit: how change value of element

    static void main(string[] args)     {         string inputfile = @"d:\temp\cat.xml";          xdocument xmldoc = xdocument.load(inputfile);         xelement root = xmldoc.root;         string val = "5";          ienumerable<xelement> vls = e in root.elements("category") e.element("categoryid").value.equals(val) select e;          if (vls.count() == 1)         {             vls.elementat(0).element("categoryname").value = "value has been changed";         }          xmldoc.save(inputfile);     } 

to further learn refer this link.