Queryable.Sum Method (IQueryable(Of Nullable(Of Double)))
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Computes the sum of a sequence of nullable Double values.
Assembly: System.Core (in System.Core.dll)
'Declaration <ExtensionAttribute> _ Public Shared Function Sum ( _ source As IQueryable(Of Nullable(Of Double)) _ ) As Nullable(Of Double)
Parameters
- source
- Type: System.Linq.IQueryable(Of Nullable(Of Double))
A sequence of nullable Double values to calculate the sum of.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable(Of Nullable(Of Double)). When you use instance method syntax to call this method, omit the first parameter.| Exception | Condition |
|---|---|
| ArgumentNullException | source is Nothing. |
The Sum(IQueryable(Of Nullable(Of Double))) method generates a MethodCallExpression that represents calling Sum(IQueryable(Of Nullable(Of Double))) itself as a constructed generic method. It then passes the MethodCallExpression to the Execute(Of 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(Of Nullable(Of 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(Of Nullable(Of Single))) to sum the values of a sequence.
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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. |
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