Collapse the table of content
Expand the table of content
Expand Minimize
The topic you requested is included in another documentation set. For convenience, it's displayed below. Choose Switch to see the topic in its original location.

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


Computes the sum of the sequence of Single 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 float Sum<TSource>(
	this IEnumerable<TSource> source,
	Func<TSource, float> selector


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

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

Type: System.Func<TSource, Single>

A transform function to apply to each element.

Return Value

Type: System.Single

The sum of the projected values.

Type Parameters


The type of the elements of source.

Exception Condition

source or selector is null.

The Sum<TSource>(IEnumerable<TSource>, Func<TSource, Single>) 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 Single.

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.


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

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
Return to top
© 2015 Microsoft