XML operation app. config class

Public class doconfig
{
Public static void editconfig (string key, string value)
{
Xmldocument xmldoc = new xmldocument ();
String filepath = application. executablepath + ". config ";
Xmldoc. Load (filepath );

Xmlnodelist topm = xmldoc. documentelement. childnodes;
Foreach (xmlelement element in topm)
{
If (element. Name. tolower () = "etettings") // locate the field name to be rewritten
{
Xmlnodelist _ node = element. childnodes;
If (_ node. Count> 0)
{
Foreach (xmlelement El in _ node)
{
// El. attributes [Key]. value = value; // search and rewrite
If (El. attributes ["key"]. value = key)
El. attributes ["value"]. value = value;
}
}
}
}
Xmldoc. Save (filepath); // Save the modified File
}
}