Sum Method (IEnumerable(Nullable(Double)))

# Enumerable.Sum Method (IEnumerable<Nullable<Double>>)

.NET Framework (current version)

Computes the sum of a sequence of nullable Double values.

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

## Syntax

```public static Nullable<double> Sum(
this IEnumerable<Nullable<double>> source
)
```

#### Parameters

source
Type:

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

#### Return Value

Type:

The sum of the values in the sequence.

## Exceptions

Exception Condition
ArgumentNullException

source is null.

## Remarks

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.

## Examples

The following code example demonstrates how to use Sum(IEnumerable<Nullable<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.

```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
*/

```

## Version Information

Universal Windows Platform
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1