Статья
11/17/2011

Queryable.Sum Method (IQueryable<Double>)

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Computes the sum of a sequence of Double values.

Namespace: System.Linq
Assembly: System.Core (in System.Core.dll)

Syntax

'Declaration
<ExtensionAttribute> _
Public Shared Function Sum ( _
    source As IQueryable(Of Double) _
) As Double

public static double Sum(
    this IQueryable<double> source
)

Parameters

source
Type: System.Linq.IQueryable<Double>
A sequence of Double values to calculate the sum of.

Return Value

Type: System.Double
The sum of the values in the sequence.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable<Double>. When you use instance method syntax to call this method, omit the first parameter.

Exceptions

Exception	Condition
ArgumentNullException	source is nulla null reference (Nothing in Visual Basic).

Remarks

The Sum(IQueryable<Double>) method generates a MethodCallExpression that represents calling Sum(IQueryable<Double>) itself as a constructed generic method. It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling Sum(IQueryable<Double>) depends on the implementation of the type of the source parameter. The expected behavior is that it returns the sum of the values in source.

Examples

The following code example demonstrates how to use Sum(IQueryable<Single>) to sum the values of a sequence.

Note:
This code example uses an overload of this overloaded method that is different from the specific overload that this topic describes. To extend the example to this topic, substitute the elements of the source sequence with elements of the appropriate numerical type.

      Dim numbers As New List(Of Single)(New Single() {43.68F, 1.25F, 583.7F, 6.5F})

      Dim sum As Single = numbers.AsQueryable().Sum()

      outputBlock.Text &= "The sum of the numbers is " & sum & vbCrLf

      ' This code produces the following output:

      ' The sum of the numbers is 635.13.

         List<float> numbers = new List<float> { 43.68F, 1.25F, 583.7F, 6.5F };

         float sum = numbers.AsQueryable().Sum();

         outputBlock.Text += String.Format("The sum of the numbers is {0}.", sum) + "\n";

         /*
             This code produces the following output:

             The sum of the numbers is 635.13.
         */

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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