Csharp/CSharp Tutorial/LINQ/Take

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Get the first four element in the list

<source lang="csharp">using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Linq.Expressions; using System.Xml.Linq;

   class Program
   {
       static void Main(string[] args)
       {
           int[] integers = { 1, 6, 2, 27, 10 };
           
           IEnumerable<int> firstFourNumbers = integers.Take(4);
           Console.WriteLine("First 4 numbers:");
           foreach (var num in firstFourNumbers)
           {
             Console.WriteLine(num);
           }
       }
   }</source>

Nested Take

<source lang="csharp">using System; using System.Collections.Generic; using System.Linq; using System.Text; public class MainClass {

   public static void Main() {
       List<Customer> customers = GetCustomerList();
       var first3WAOrders = (
           from c in customers
           from o in c.Orders
           where c.Region == "R1"
           select new { c.CustomerId, o.Id, o.OrderDate })
           .Take(3);
       Console.WriteLine("First 3 orders in WA:");
       foreach (var order in first3WAOrders) {
           Console.WriteLine(order);
       }
   }
   static List<Customer> GetCustomerList() {
       List<Product> empTree = new List<Product>();
       empTree.Add(new Product { ProductName = "A", Category = "O", UnitPrice = 12, UnitsInStock = 5, Total = 36, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
       empTree.Add(new Product { ProductName = "B", Category = "O", UnitPrice = 2, UnitsInStock = 4, Total = 35, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
       empTree.Add(new Product { ProductName = "C", Category = "O", UnitPrice = 112, UnitsInStock = 3, Total = 34, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
       empTree.Add(new Product { ProductName = "D", Category = "O", UnitPrice = 112, UnitsInStock = 0, Total = 33, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
       empTree.Add(new Product { ProductName = "E", Category = "O", UnitPrice = 1112, UnitsInStock = 2, Total = 32, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
       empTree.Add(new Product { ProductName = "F", Category = "O", UnitPrice = 11112, UnitsInStock = 0, Total = 31, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
       List<Customer> l = new List<Customer>();
       l.Add(new Customer { CompanyName = "A", Region = "R1", UnitsInStock = 1, Orders = empTree, CustomerId = 0 });
       l.Add(new Customer { CompanyName = "B", Region = "R2", UnitsInStock = 2, Orders = empTree, CustomerId = 1 });
       l.Add(new Customer { CompanyName = "C", Region = "R3", UnitsInStock = 3, Orders = empTree, CustomerId = 2 });
       l.Add(new Customer { CompanyName = "D", Region = "R4", UnitsInStock = 4, Orders = empTree, CustomerId = 3 });
       l.Add(new Customer { CompanyName = "E", Region = "R5", UnitsInStock = 5, Orders = empTree, CustomerId = 4 });
       return l;
   }

} class Customer : IComparable<Customer> {

   public string CompanyName { get; set; }
   public string Region { get; set; }
   public List<Product> Orders { get; set; }
   public int UnitsInStock { get; set; }
   public int CustomerId { get; set; }
   public override string ToString() {
       return String.Format("Id: {0}, Name: {1}, Region: {3}", this.CustomerId, this.rupanyName, this.Region);
   }
   int IComparable<Customer>.rupareTo(Customer other) {
       if (other == null)
           return 1;
       if (this.CustomerId > other.CustomerId)
           return 1;
       if (this.CustomerId < other.CustomerId)
           return -1;
       return 0;
   }

} class Product : IComparable<Product> {

   public string ProductName { get; set; }
   public string Category { get; set; }
   public int UnitPrice { get; set; }
   public int UnitsInStock { get; set; }
   public int Total { get; set; }
   public DateTime OrderDate { get; set; }
   public int Id { get; set; }
   public override string ToString() {
       return String.Format("Id: {0}, Name: {1} , Category: {3}", this.Id, this.ProductName, this.Category);
   }
   int IComparable<Product>.rupareTo(Product other) {
       if (other == null)
           return 1;
       if (this.Id > other.Id)
           return 1;
       if (this.Id < other.Id)
           return -1;
       return 0;
   }

}</source>

Partitioning Operators: uses Take to generate a sequence of the first three elements of an integer array.

<source lang="csharp">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 first3Numbers = numbers.Take(3);
       Console.WriteLine("First 3 numbers:");
       foreach (var n in first3Numbers) {
           Console.WriteLine(n);
       }
   }

}</source>

Take and SelectMany

<source lang="csharp">using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass {

   public static void Main() {
       string[] presidents = {"Aaa", "Art", "Buch", "Bushman", "Carter", "land"};
       IEnumerable<char> chars = presidents.Take(5).SelectMany(s => s.ToArray());
       foreach (char ch in chars)
           Console.WriteLine(ch);
   }

}</source>

Take method

<source lang="csharp">using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass {

   public static void Main() {
       string[] presidents = {"A", "A", "B", "Bu", "Car", "land"};
       IEnumerable<string> items = presidents.Take(5);
       foreach (string item in items)
           Console.WriteLine(item);
   }

}</source>

Take operator outputs the first x elements, discarding the rest

<source lang="csharp">using System; using System.Collections.Generic; using System.Linq; public class MainClass {

   public static void Main() {
       int[] numbers = { 10, 9, 8, 7, 6 };
       IEnumerable<int> firstThree = numbers.Take(3);     // { 10, 9, 8 }
   }

}</source>

Use Take

<source lang="csharp">using System; using System.Collections; using System.Collections.Generic; using System.Text; using System.Linq; public class MainClass{

  public static void Main(){
      int[] numbers = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
      var query = numbers.Take(5);
      var query2 = numbers.Skip(5);
   }

}</source>