using System; using System.Collections.Generic; using System.Linq; public class MainClass { public static void Main() { string[] names = { "Tom", "Dick", "Harry", "Mary", "Jay" }; IEnumerable<string> filtered = names.Where(n => n.Contains("a")); IEnumerable<string> sorted = filtered.OrderBy(n => n.Length); IEnumerable<string> finalQuery = sorted.Select(n => n.ToUpper()); foreach (string name in filtered) Console.Write(name + "|"); Console.WriteLine(); foreach (string name in sorted) Console.Write(name + "|"); Console.WriteLine(); foreach (string name in finalQuery) Console.Write(name + "|"); } }
Chaining Query Operators/extracts all strings containing the letter “a”, sorts them by length, and then converts the results to uppercase
using System; using System.Collections.Generic; using System.Linq; class LinqDemo { static void Main() { string[] names = { "J", "P", "G", "P" }; IEnumerable<string> query = names .Where(n => n.Contains("a")) .OrderBy(n => n.Length) .Select(n => n.ToUpper()); foreach (string name in query) Console.Write(name + "|"); } }
First Select Prototype
using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass { public static void Main() { string[] presidents = {"A", "Ar", "Buc", "Bush", "Carte", "Clevel"}; var nameObjs = presidents.Select(p => new { p, p.Length }); foreach (var item in nameObjs) Console.WriteLine(item); } }
Select Prototype: string length
using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass { public static void Main() { string[] presidents = {"A", "Ar", "Buc", "Bush", "Carte", "Clevel"}; var nameObjs = presidents.Select(p => new { LastName = p, Length = p.Length }); foreach (var item in nameObjs) Console.WriteLine("{0} is {1} characters long.", item.LastName, item.Length); } }
Second Select Prototype
using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass { public static void Main() { string[] presidents = {"A", "B", "Bu", "Bush", "C", "Cl"}; var nameObjs = presidents.Select((p, i) => new { Index = i, LastName = p }); foreach (var item in nameObjs) Console.WriteLine("{0}. {1}", item.Index + 1, item.LastName); } }
Where by Prototype
using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass { public static void Main() { string[] presidents = {"Ad", "Ar", "Bu", "Bu", "Ca", "Cl"}; IEnumerable<string> sequence = presidents.Where((p, i) => (i & 1) == 1); foreach (string s in sequence) Console.WriteLine("{0}", s); } }
Projection Operators: do calculation in select statement
using System; using System.Collections.Generic; using System.Linq; using System.Text; public class MainClass { public static void Main() { int[] numbers = { 5, 4, 1, 3, 9}; var numsPlusOne = from n in numbers select n + 1; Console.WriteLine("Numbers + 1:"); foreach (var i in numsPlusOne) { Console.WriteLine(i); } } }