C# Linq FirstorDefault Method

Use the FirstorDefault() method to return the first element of a sequence or a default value if element isn’t there.

The following is our empty list −

List<double> val = new List<double> { };

Now, we cannot display the first element, since it is an empty collection. For that, use the FirstorDefault() method to display the default value.

val.AsQueryable().FirstOrDefault();

The following is the complete example.

Example

 Live Demo

using System; using System.Collections.Generic; using System.Linq; class Demo {    static void Main() {       List<double> val = new List<double> { };       double d = val.AsQueryable().FirstOrDefault();       Console.WriteLine("Default Value = "+d);       if (d == 0.0D) {          d = 0.1D;       }       Console.WriteLine("Default Value changed = "+d);    } }

Output

Default Value = 0 Default Value changed = 0.1