C# — LINQ

Basic LINQ

using System.Linq;

var nums = new[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

var evens = nums.Where(n => n % 2 == 0);
var doubled = nums.Select(n => n * 2);
var sum = nums.Sum();
var avg = nums.Average();

Query syntax

var result = from n in nums
             where n > 5
             orderby n descending
             select n;

Chaining

var result = nums
    .Where(n => n % 2 == 0)
    .Select(n => n * n)
    .Take(3)
    .ToList();

GroupBy

var groups = nums.GroupBy(n => n % 2 == 0 ? "Even" : "Odd");
foreach (var group in groups)
{
    Console.WriteLine($"{group.Key}: {string.Join(", ", group)}");
}

Mini Practice

Write C# code that:

1. Uses Where to filter
2. Uses Select to transform
3. Chains multiple operations
4. Uses GroupBy

Up Next

In the next lesson, you'll learn about Async Await — asynchronous programming.