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Enumerable.Sum<TSource> Method (IEnumerable<TSource>, Func<TSource, Nullable<Decimal>>)

Visual Studio 2008

Computes the sum of the sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence.

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

Syntax

```public static Nullable<decimal> Sum<TSource>(
this IEnumerable<TSource> source,
Func<TSource, Nullable<decimal>> selector
)
```

Type Parameters

TSource

The type of the elements of source.

Parameters

source
Type: System.Collections.Generic.IEnumerable<TSource>

A sequence of values that are used to calculate a sum.

selector
Type: System.Func<TSource, Nullable<Decimal>>

A transform function to apply to each element.

Return Value

Type: System.Nullable<Decimal>
The sum of the projected values.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<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).

Exceptions

ExceptionCondition
ArgumentNullException

source or selector is null.

OverflowException

The sum is larger than MaxValue.

Remarks

This method returns zero if source contains no elements.

The result does not included values that are null.

You can apply this method to a sequence of arbitrary values if you provide a function, selector, that projects the members of source into a numeric type, specifically Nullable<Decimal> in C# or Nullable(Of Decimal) in Visual Basic.

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<TSource>(IEnumerable<TSource>, 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.

```class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}

public static void SumEx1()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };

double totalWeight = packages.Sum(pkg => pkg.Weight);

Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
This code produces the following output:

The total weight of the packages is: 83.7
*/
```

Platforms

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.

Version Information

.NET Framework

Supported in: 3.5

.NET Compact Framework

Supported in: 3.5

XNA Framework

Supported in: 3.0
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