Retrieving an element from a sequence with an index in LINQ C#

Say you have the following Singer object and sequence of Singers:

public class Singer
{
	public int Id { get; set; }
	public string FirstName { get; set; }
	public string LastName { get; set; }
	public int BirthYear { get; set; }
}

IEnumerable<Singer> singers = new List<Singer>() 
		{
			new Singer(){Id = 1, FirstName = "Freddie", LastName = "Mercury", BirthYear=1964}
			, new Singer(){Id = 2, FirstName = "Elvis", LastName = "Presley", BirthYear = 1954}
			, new Singer(){Id = 3, FirstName = "Chuck", LastName = "Berry", BirthYear = 1954}
			, new Singer(){Id = 4, FirstName = "Ray", LastName = "Charles", BirthYear = 1950}
			, new Singer(){Id = 5, FirstName = "David", LastName = "Bowie", BirthYear = 1964}
		};

Say you want to get to the second element of the singers sequence. You can use the ElementAt operator to achieve that. As all arrays and lists are 0 based, then the second element has index = 1:

Singer singer = singers.ElementAt(1);
Console.WriteLine(singer.LastName);

The operator has found Elvis Presley. If there’s no element at the specified index then an ArgumentOutOfRangeException is thrown. To avoid that you can use the ElementAtOrDefault operator instead:

Singer singer = singers.ElementAtOrDefault(100);
Console.WriteLine(singer == null ? "No such singer" : singer.LastName);

…which prints “No such singer”.

View the list of posts on LINQ here.

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About Andras Nemes
I'm a .NET/Java developer living and working in Stockholm, Sweden.

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