Csharp/C Sharp by API/System.Linq/Enumerable

Enumerable.Aggregate

 

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.Aggregate((a, b) => a * b);
    }
}

Enumerable.Average()

 
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, 8, 6, 7, 2, 0 };
        double averageNum = numbers.Average();
        Console.WriteLine("The average number is {0}.", averageNum);
    }
}

Enumerable.Cast

  
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Linq;
public class MainClass{
   public static void Main(){
            object[] doubles = {1.0, 2.0, 3.0};
            IEnumerable<double> d = doubles.Cast<double>();
            Console.Write(d);
   }
}

Enumerable.Count()

  
using System;
using System.Collections.Generic;
using System.Linq;
static class TestString {
    static void Main() {
        var count =
          "abc 8"
          .Where(c => !Char.IsLetter(c))
          .Count();
        Console.WriteLine(count);
    }
}

Enumerable.DefaultIfEmpty

 
using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class MainClass {
    public static void Main() {
        string[] presidents = {"G", "H", "a", "H", "over", "Jack"};
        string name =
          presidents.Where(n => n.Equals("H")).DefaultIfEmpty("Missing").First(); Console.WriteLine(name);
    }
}

Enumerable.Distinct()

 
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, 1, 2, 3, 3};
            Console.Write(numbers.Distinct());
   }
}

Enumerable.ElementAt

 
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.ElementAt(4);
            Console.Write(query);
   }
}

Enumerable.ElementAtOrDefault

 
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.ElementAtOrDefault(9);
            Console.Write(query);
   }
}

Enumerable.ElementsAfterSelf

 

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using System.Xml;
using System.Xml.Linq;
public class MainClass {
    public static void Main() {
        XElement firstParticipant;
        XDocument xDocument = new XDocument(
         new XDeclaration("1.0", "UTF-8", "yes"),
       new XDocumentType("Books", null, "Books.dtd", null),
       new XProcessingInstruction("Book", "out-of-print"),
       new XElement("Books",
      new XComment("Begin Of List"), firstParticipant =
       new XElement("Book",
       new XAttribute("type", "Author"),
       new XElement("FirstName", "J"),
       new XElement("LastName", "R")),
       new XElement("Book",
       new XAttribute("type", "Author"),
       new XElement("FirstName", "E"),
       new XElement("LastName", "B")),
       new XComment("End Of List")));
        foreach (XNode node in firstParticipant.ElementsAfterSelf()) {
            Console.WriteLine(node);
        }
    }
}

Enumerable.Empty

 
using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class MainClass {
    public static void Main() {
        IEnumerable<string> strings = Enumerable.Empty<string>();
        foreach (string s in strings)
            Console.WriteLine(s); Console.WriteLine(strings.Count());
    }
}

Enumerable.First

 
using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class MainClass {
    public static void Main() {
        string[] presidents = {"G", "H", "a", "H", "over", "Jack"};
        string jones = presidents.Where(n => n.Equals("H")).First();
        if (jones != null)
            Console.WriteLine("H was found");
        else
            Console.WriteLine("H was not found");
    }
}

Enumerable.OrderBy

  
using System;
using System.Linq;
static class TestArray {
    static void Main() {
        Object[] array = { "String", 12, true, "a" };
        var types =
          array
            .Select(item => item.GetType().Name)
            .OrderBy(type => type);
    }
}

Enumerable.Range

 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
public class MainClass {
    public static void Main() {
        var numbers =
           from n in Enumerable.Range(100, 50)
           select new { Number = n, OddEven = n % 2 == 1 ? "odd" : "even" };
        foreach (var n in numbers) {
            Console.WriteLine("The number {0} is {1}.", n.Number, n.OddEven);
        }
    }
}

Enumerable.Repeat

 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
public class MainClass {
    public static void Main() {
        var numbers = Enumerable.Repeat(7, 10);
        foreach (var n in numbers) {
            Console.WriteLine(n);
        }
    }
}

Enumerable.Where

  
using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class MainClass {
    public static void Main() {
        string[] strings = { "one", "two", null, "three" };
        Console.WriteLine("Before Where() is called.");
        IEnumerable<string> ieStrings = strings.Where(s => s.Length == 3);
        Console.WriteLine("After Where() is called.");
        foreach (string s in ieStrings) {
            Console.WriteLine("Processing " + s);
        }
    }
}