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

.NET Framework 4.5

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
Assemblies:   System.Linq (in System.Linq.dll)
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
*/
```

Version Information

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0

.NET for Windows Phone apps

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

Portable Class Library

Supported in: Portable Class Library