# Enumerable.Sum Method (IEnumerable(Of Nullable(Of Int64)))

.NET Framework 4.5

Computes the sum of a sequence of nullable Int64 values.

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

## Syntax

```'Declaration
<ExtensionAttribute> _
Public Shared Function Sum ( _
source As IEnumerable(Of Nullable(Of Long)) _
) As Nullable(Of Long)
```

#### Parameters

source
Type: System.Collections.Generic.IEnumerable(Of Nullable(Of Int64))

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

#### Return Value

Type: System.Nullable(Of 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(Of Nullable(Of 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).

## Exceptions

ExceptionCondition
ArgumentNullException

source is Nothing.

OverflowException

The sum is larger than MaxValue.

## Remarks

This method returns zero if source contains no elements.

The result does not include values that are Nothing.

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

## Examples

The following code example demonstrates how to use Sum(IEnumerable(Of Nullable(Of Single))) to sum the 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, substitute the elements of the source sequence with elements of the appropriate numerical type.

```        ' Create an array of Nullable Single values.
Dim points() As Nullable(Of Single) = _
{Nothing, 0, 92.83F, Nothing, 100.0F, 37.46F, 81.1F}

' Get the sum of values in the list.
Dim sum As Nullable(Of Single) = points.Sum()

' Display the output.
MsgBox("Total points earned: " & sum)

' This code produces the following output:
'
' Total points earned: 311.39
```

## Version Information

#### .NET Framework

Supported in: 4.6, 4.5, 4, 3.5

#### .NET Framework Client Profile

Supported in: 4, 3.5 SP1

#### Portable Class Library

Supported in: Portable Class Library

#### .NET for Windows Store apps

Supported in: Windows 8
Supported in: Windows Phone 8.1
Supported in: Windows Phone Silverlight 8.1
Supported in: Windows Phone Silverlight 8

## Platforms

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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