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

Computes the sum of the sequence of Double 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)

public static double Sum<TSource>(
	this IEnumerable<TSource> source,
	Func<TSource, double> 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, Double>

A transform function to apply to each element.

Return Value

Type: System.Double
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).

ExceptionCondition
ArgumentNullException

source or selector is null.

This method returns zero if source contains no elements.

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 Double.

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<TSource>(IEnumerable<TSource>, Func<TSource, Double>) to sum the projected values of a sequence.

            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
            */

.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
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