Single

In this chapter you will learn:

How to use Single operator
SingleOrDefault vs Single

Get to Single operator

using System;// java 2  s.  c  om
using System.Linq;

public class MainClass{
   public static void Main(){
            int[] numbers = {1, 2, 3, 4, 5, 6, 7, 8, 9};
            var query = numbers.Single(n => n > 8);
            Console.Write(query);
   }
}

SingleOrDefault vs Single

To avoid an exception, Single requires exactly one matching element;

SingleOrDefault requires one or zero matching elements:

using System;/* j  av  a  2s  .c o  m*/
using System.Collections;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        int[] numbers = { 1, 2, 3, 4, 5 };

        int v = numbers.Single(n => n % 3 == 0);
        v = numbers.Single(n => n % 2 == 0);

        Console.WriteLine(v);
        v = numbers.Single(n => n > 10);
        v = numbers.SingleOrDefault(n => n > 10);
        v = numbers.SingleOrDefault(n => n % 2 == 0);  
        Console.WriteLine(v);
    }
}

The output:

Next chapter...

What you will learn in the next chapter:

How to use SingleOrDefault operator