Sum Method (IEnumerable(Nullable(Int64)))

Enumerable.Sum Method (IEnumerable<Nullable<Int64>>)

Computes the sum of a sequence of nullable Int64 values.

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

public static Nullable<long> Sum(
	this IEnumerable<Nullable<long>> source


Type: System.Collections.Generic.IEnumerable<Nullable<Int64>>

A sequence of nullable Int64 values to calculate the sum of.

Return Value

Type: System.Nullable<Int64>
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 IEnumerable<Nullable<Int64>>. 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).


source is null.


The sum is larger than MaxValue.

This method returns zero if source contains no elements.

The result does not include values that are null.

In Visual Basic query expression syntax, an Aggregate Into Sum() clause translates to an invocation of Sum.

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


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.Sum();

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

 This code produces the following output:

 Total points earned: 311.39

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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.

.NET Framework

Supported in: 3.5

.NET Compact Framework

Supported in: 3.5

XNA Framework

Supported in: 3.0

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