Applied XML Programming for Microsoft .NET.pdf - Csbdu.in

string colName =XmlConvert.DecodeName("Invoice_0x0020_Details");The only valid form of hexadecimal sequences is _0xHHHH_, where HHHH stands fora four-digit hexadecimal value. Similar forms are left unaltered, although they couldeasily be considered logically equivalent—for example, _0x20_ is not processed.Character EncodingXML documents can contain an attribute to specify the encoding. Character encodingprovides a mapping between numeric indexes and corresponding characters that usersread from a document. The following declaration shows how to set the requiredencoding for an XML document:The Encoding property of the XML reader returns the character encoding found in thedocument. The default encoding attribute is UTF-8 (UCS Transformation Format, 8bits).In the .NET Framework, the System.Text.Encoding class gathers all supportedencodings. Most of these encodings can be used with XML documents, with just a fewexceptions. Encodings such as UTF-7 are invalid for XML documents because theyrequire different byte values than UTF-8. UTF-8 encodes Unicode characters using 8bits per character. UTF-7, on the other hand, encodes Unicode characters using 7 bitsper character.Accessing AttributesOf all the node types supplied in the .NET Framework, only Element, DocumentType,and XmlDeclaration support attributes. To check whether a given node containsattributes, use the HasAttributes Boolean property. The AttributeCount property returnsthe number of attributes available for the current node.Once the internal reader's pointer is positioned on a certain node, you can directly readthe value of a particular attribute using either the GetAttribute method or the indexerproperty Item. In both cases, overloads of the method and the property allow you toaccess attributes in various ways: by absolute position, by name, and by name andnamespace. The returned value for an attribute is always a string; the task of convertingit to a more specific data type is left to the programmer.GetAttribute and Item provide a way to access attributes directly but require that youknow the name or the ordinal position of the attribute being accessed. A third way toread attribute values is by moving the pointer to the attribute node itself and then usingthe Value property. You enumerate the attribute nodes using the MoveToFirstAttributeand MoveToNextAttribute methods. You can also change the pointer by moving directlyto a given node using the MoveToAttribute method.This next example demonstrates how to programmatically access any sequence ofattributes for a node and concatenate their names and values in a single string.Consider the following XML fragment:We want to create a method that, when run on this XML block of data, generates thefollowing string:id="1" lastname="Users" firstname="Joe"32