Function Var2Xml() Foundation

The function Var2Xml() converts values of all data types to an XML-encoded character string, which includes both the data type and the value of the passed argument. The return value of Var2Xml() can be transformed back to the original value by passing it to the function Xml2Var().

This allows, for example, the exchange of data between different applications, specifically over Internet protocols, as well as storing data in a transparent, text-based, human-readable, and editable format.

Conversion of data types

Empty values are always represented by a single data type-specific XML element, in the format: <datatype/>, while not-empty values are first converted into their textual representation, and then enclosed in data type-specific XML start and end tags, to create an XML element in the format: <datatype>value</datatype>.

Date values: Date values use DtoS() format (YYYYMMDD).

Character strings: Strings are XML-escaped. The following conversion table below shows which characters are XML-escaped and how they appear after conversion.

If a character string only contains white-space characters, it will be considered empty!

Code blocks: Code blocks shouldn't contain any STATIC or detached LOCAL variables, as any references to those variables are lost during the conversion.

Arrays: All array elements are listed as individual XML child elements, based on their data types and values, between the start and end tags of the array's XML element. Because child elements can represent any supported data type, they can themselves contain child elements, to describe multi-dimensional arrays or objects. For example, the array: {123.5, .t., "Test"} with three array elements would be represented by the following XML fragment:

<array> 
   <numeric>123.5</numeric> 
   <logical>true</logical> 
   <character>Test</character> 
</array> 

An array without elements is considered an empty value.

Objects: With regard to objects, the function Var2Xml() accepts only instances objects. When an object is converted to XML, the class name and the names of its exported instance variables are also encoded in the XML tags as XML Attributes. An object is represented by the XML start and end tags <object classname="<ClassName>"> and </object>. An object without any exported instance variables is considered an empty value.

All instance variables of an object are listed as individual XML child elements, based on their data types and values, between the start and end tags of the object's XML element. Each instance variable's start tag also contains a name attribute, which specifies the instance variable's name, such as: <array name="<iVarName>">. Because child elements can represent any supported data type, they can themselves contain child elements, to describe arrays or other objects. For example, an object of the class DataObject with a single instance variable named TextVar, which has a character string value of "Test", would be represented by the following XML fragment:

<object classname="DataObject"> 
   <character name="TextVar">Test</character> 
</object>