C# 4 and .NET 4

eading and Writing streamed XMl ❘ 909
private void button5_Click(object sender, EventArgs e)
{
richTextBox1.Clear();
XmlReader rdr = XmlReader.Create("books.xml");
while (rdr.Read())
{
if (rdr.NodeType == XmlNodeType.Element)
{
if (rdr.Name == "price")
{
decimal price = rdr.ReadElementContentAsDecimal();
richTextBox1.AppendText("Current Price = " + price + "\r\n");
price += price * (decimal).25;
richTextBox1.AppendText("New Price = " + price + "\r\n\r\n");
}
else if(rdr.Name== "title")
richTextBox1.AppendText(rdr.ReadElementContentAsString() + "\r\n");
}
}
}
code download XMLReaderSample.sln
If the value cannot be converted to a decimal value, a FormatException is raised. This is a much more
efficient method than reading the value as a string and casting it to the proper data type.
retrieving attribute Data
As you play with the sample code, you might notice that when the nodes are read in, you don’t see
any attributes. This is because attributes are not considered part of a document’s structure. When
you are on an element node, you can check for the existence of attributes and optionally retrieve the
attribute values.
For example, the HasAttributes property returns true if there are any attributes; otherwise, it returns
false. The AttributeCount property tells you how many attributes there are, and the GetAttribute()
method gets an attribute by name or by index. If you want to iterate through the attributes one at a time,
you can use the MoveToFirstAttribute() and MoveToNextAttribute() methods.
The following is an example of iterating through the attributes of the books.xml document:
private void button7_Click(object sender, EventArgs e)
{
richTextBox1.Clear();
XmlReader tr = XmlReader.Create("books.xml");
//Read in node at a time
while (tr.Read())
{
//check to see if it's a NodeType element
if (tr.NodeType == XmlNodeType.Element)
{
//if it's an element, then let's look at the attributes.
for (int i = 0; i < tr.AttributeCount; i++)
{
richTextBox1.AppendText(tr.GetAttribute(i) + "\r\n");
}
}
}
}
code download XMLReaderSample.sln
www.it-ebooks.info