Aggregate. This C# method applies a method to each element. It applies a function to each successive element. We specify the function with a Func (often with lambda syntax).
With this extension method, we act upon the aggregate of all previous elements. This makes certain methods, such as sum, possible.
Add example. The first call uses a Func that specifies that the accumulation should be added to the next element. This simply results in the sum of all the elements in the array.
Detail With Aggregate we "accumulate" values, meaning we build up values from each previous function call.
using System;
using System.Linq;
int[] array = { 1, 2, 3, 4, 5 };
int result = array.Aggregate((a, b) => b + a);
// 1 + 2 = 3// 3 + 3 = 6// 6 + 4 = 10// 10 + 5 = 15
Console.WriteLine(result);15
Multiply example. The second call is more interesting. It multiplies the accumulation with the next element. The difference between adding and multiplying is significant.
using System;
using System.Linq;
int[] array = { 1, 2, 3, 4, 5 };
int result = array.Aggregate((a, b) => b * a);
// 1 * 2 = 2// 2 * 3 = 6// 6 * 4 = 24// 24 * 5 = 120
Console.WriteLine(result);120
Func. The Aggregate method receives a higher-order procedure of type Func. The Func receives 2 arguments and returns a third. This is the accumulator function.
Extensions. Aggregate() is the first method listed in Visual Studio on many collections (like arrays). Visual Studio is presenting extension methods.
So The list of methods, starting with Aggregate, are methods from a namespace called System.Linq.
Summary. Aggregate is a declarative way of applying an accumulator function to a collection of elements. It can multiply or add all elements together.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
This page was last updated on May 25, 2023 (edit).
