DefaultIfEmpty

In this chapter you will learn:

How to use DefaultIfEmpty operator
Use DefaultIfEmpty after where clause

Get to know DefaultIfEmpty operator

Returns the elements of the specified sequence or just returns the type parameter's default value in a singleton collection if the sequence is empty.

using System;//from jav  a  2 s  .c o  m
using System.Linq;
using System.Collections;
using System.Collections.Generic;

public class MainClass {
   public static void Main() {
      List<int> numbers = new List<int>();

      foreach (int number in numbers.DefaultIfEmpty()){
         Console.WriteLine(number);
      }
   }
}

DefaultIfEmpty after where clause

using System;/*from   j  a v a2s.c o  m*/
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")).DefaultIfEmpty().First();
        if (jones != null)
            Console.WriteLine("H was found.");
        else
            Console.WriteLine("H was not found.");
    }
}

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What you will learn in the next chapter: