Queryable.Sum Method (IQueryable<Nullable<Double>>)

Computes the sum of a sequence of nullable Double values.

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

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

Parameters

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

Return Value

Type: System.Nullable<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<Nullable<Double>>. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

ExceptionCondition
ArgumentNullException

source is null.

The Sum(IQueryable<Nullable<Double>>) method generates a MethodCallExpression that represents calling Sum(IQueryable<Nullable<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<Nullable<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.

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

NoteNote

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.


            float?[] points = { null, 0, 92.83F, null, 100.0F, 37.46F, 81.1F };

            float? sum = points.AsQueryable().Sum();

            Console.WriteLine("Total points earned: {0}", sum);

            /*
                This code produces the following output:

                Total points earned: 311.39
            */



.NET Framework

Supported in: 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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