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

XmlTextWriter provides a standard implementation for all the methods and theproperties described up to now, plus a few more. It maintains an internal stack to keeptrack of XML elements that have been opened but not yet closed. Each element nodecan be directly associated with a namespace, thus becoming the root of a namespacescope. If a namespace is not specified, the element is associated with the last declarednamespace.The XmlTextWriter class has three constructors. You can have the writer work on a fileor on an open stream. In both cases, you must also specify the required encodingschema, as shown in the following code. If this argument is null, the UniversalCharacter Set Transformation Format, 8-bit form (UTF-8) character encoding set isassumed.public XmlTextWriter(Stream w, Encoding encoding);public XmlTextWriter(string filename, Encoding encoding);The third constructor allows you build an XML text writer starting from a TextWriterobject.Encoding SchemasIn the .NET Framework, four different character encoding schemas are defined. Eachschema corresponds to a class that inherits from the Encoding class. The classes arelisted in Table 4-6.Table 4-6: Available Character Encoding SchemasProperty Class DescriptionEncoding.ASCII ASCIIEncoding Encodes Unicode charactersas single 7-bit ASCIIcharacters.Encoding.Unicode UnicodeEncoding Encodes each Unicodecharacter as two consecutivebytes.Encoding.UTF7 UTF7Encoding Encodes Unicode charactersusing the UTF-7 characterencoding set. (UTF-7 standsfor Universal Character SetTransformation Format, 7-bitform.)Encoding.UTF8 UTF8Encoding Encodes Unicode charactersusing the UTF-8 characterencoding set.The default character encoding schema is UTF-8, which supports all Unicode charactervalues and surrogates. UTF-8 uses a variable number of bytes per character and isoptimized for the lower 127 ASCII characters.If you want to use the default encoding, omit the second argument in the constructor.Otherwise, use the static properties of the Encoding class to indicate which type ofencoding you want. You don't need to create a new instance of an encoding class tocreate a writer that encodes data in a certain way. For example, to create an ASCIIstream, you use the following code:XmlTextWriter xmlw = new XmlTextWriter(file, Encoding.ASCII);119