Uređivanje

Dijeli putem

How to calculate intermediate values (LINQ to XML)

  • Članak

This article shows how to calculate intermediate values for use in sorting, filtering, and selecting in C# and Visual Basic.

Example: Use the let clause to calculate based on element data

The following example uses the let clause to calculate products of numerical values from elements. It uses XML document Sample XML file: Numerical data.

XElement root = XElement.Load("Data.xml");
IEnumerable<decimal> extensions =
    from el in root.Elements("Data")
    let extension = (decimal)el.Element("Quantity") * (decimal)el.Element("Price")
    where extension >= 25
    orderby extension
    select extension;
foreach (decimal ex in extensions)
    Console.WriteLine(ex);

Dim root As XElement = XElement.Load("Data.xml")
Dim extensions As IEnumerable(Of Decimal) = _
    From el In root.<Data> _
    Let extension = CDec(el.<Quantity>.Value) * CDec(el.<Price>.Value) _
    Where extension > 25 _
    Order By extension _
    Select extension
For Each ex As Decimal In extensions
    Console.WriteLine(ex)
Next

This example produces the following output:

55.92
73.50
89.99
198.00
435.00

Example: Calculate from XML that's in a namespace

The following example shows the same query as before, but for XML that's in a namespace. It uses the XML document Sample XML file: Numerical data in a namespace.

For more information, see Namespaces overview.

XElement root = XElement.Load("DataInNamespace.xml");
XNamespace ad = "http://www.adatum.com";
IEnumerable<decimal> extensions =
    from el in root.Elements(ad + "Data")
    let extension = (decimal)el.Element(ad + "Quantity") * (decimal)el.Element(ad + "Price")
    where extension >= 25
    orderby extension
    select extension;
foreach (decimal ex in extensions)
    Console.WriteLine(ex);

Imports <xmlns="http://www.adatum.com">

Module Module1
    Sub Main()
        Dim root As XElement = XElement.Load("DataInNamespace.xml")
        Dim extensions As IEnumerable(Of Decimal) = _
            From el In root.<Data> _
            Let extension = CDec(el.<Quantity>.Value) * CDec(el.<Price>.Value) _
            Where extension > 25 _
            Order By extension _
            Select extension
        For Each ex As Decimal In extensions
            Console.WriteLine(ex)
        Next
    End Sub
End Module

This example produces the following output:

55.92
73.50
89.99
198.00
435.00

See also