Queryable::Sum<TSource> Method (IQueryable<TSource>, Expression<Func<TSource, Single>>)
Computes the sum of the sequence of Single values that is obtained by invoking a projection function on each element of the input sequence.
Assembly: System.Core (in System.Core.dll)
[ExtensionAttribute] public: generic<typename TSource> static float Sum( IQueryable<TSource>^ source, Expression<Func<TSource, float>^>^ selector )
Type Parameters
- TSource
The type of the elements of source.
Parameters
- source
- Type: System.Linq::IQueryable<TSource>
A sequence of values of type TSource.
- selector
- Type: System.Linq.Expressions::Expression<Func<TSource, Single>>
A projection function to apply to each element.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable<TSource>. 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).| Exception | Condition |
|---|---|
| ArgumentNullException | source or selector is nullptr. |
This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T, TResult> types. For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.
The Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource, Single>>) method generates a MethodCallExpression that represents calling Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource, Single>>) 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<TSource>(IQueryable<TSource>, Expression<Func<TSource, Single>>) depends on the implementation of the type of the source parameter. The expected behavior is that it invokes selector on each element of source and returns the sum of the resulting values.
The following code example demonstrates how to use Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource, Double>>) to sum the projected 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, change the body of the selector function. |
Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
Note: