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.

Exception Condition

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

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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