using System; using System.Collections; using System.Collections.Generic; using System.Text; using System.Linq; using System.Reflection; class Person { int _id; int _idRole; string _lastName; string _firstName; public int ID { get { return _id; } set { _id = value; } } public int IDRole { get { return _idRole; } set { _idRole = value; } } public string LastName { get { return _lastName; } set { _lastName = value; } } public string FirstName { get { return _firstName; } set { _firstName = value; } } } class Program { static void Main(string[] args) { List<Person> people = new List<Person> { new Person { ID = 1, IDRole = 1, LastName = "A", FirstName = "B"}, new Person { ID = 2, IDRole = 2, LastName = "G", FirstName = "T"}, new Person { ID = 3, IDRole = 2, LastName = "G", FirstName = "M"}, new Person { ID = 4, IDRole = 3, LastName = "C", FirstName = "G"} }; var query = people.Where((p, index) => p.IDRole == index); } }
Query string value by String.StartsWith
using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass { public static void Main() { string[] presidents = {"Ad", "Ar", "Bu", "B", "C", "C"}; string president = presidents.Where(p => p.StartsWith("Ad")).First(); Console.WriteLine(president); } }
Where clause with string method and return IEnumerable object
using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass { public static void Main() { string[] presidents = {"AA", "A", "AAA", "B", "Ca", "C"}; IEnumerable<string> items = presidents.Where(p => p.StartsWith("A")); foreach (string item in items) Console.WriteLine(item); } }
Query with an Exception
using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass { public static void Main() { string[] presidents = {"AAAA", "aaaa", "bacDert", "B1234", "Carter"}; IEnumerable<string> items = presidents.Where(s => Char.IsLower(s[4])); Console.WriteLine("After the query."); foreach (string item in items) Console.WriteLine(item); } }
Use string method in where clause
using System; using System.Linq; public class MainClass { public static void Main() { string[] greetings = { "hello world", "hello LINQ", "hello" }; var items = from s in greetings where s.EndsWith("LINQ") select s; foreach (var item in items) Console.WriteLine(item); } }
To remove all vowels from a string.
using System; using System.Collections.Generic; using System.Linq; public class MainClass { public static void Main() { IEnumerable<char> query = "Not what you might expect"; query = query.Where(c => c != 'a'); query = query.Where(c => c != 'e'); query = query.Where(c => c != 'i'); query = query.Where(c => c != 'o'); query = query.Where(c => c != 'u'); foreach (char c in query) Console.Write(c); } }
A Query Using the Standard Dot Notation Syntax
using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass { public static void Main() { string[] names = { "A1", "B123", "C123123", "E", "W" }; IEnumerable<string> sequence = names .Where(n => n.Length < 6) .Select(n => n); foreach (string name in sequence) { Console.WriteLine("{0}", name); } } }