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

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

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.

Type Parameters

TSource

The type of the elements of source.

Exception Condition
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
*/

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
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