Csharp/C Sharp/LINQ/ElementAtOrDefault
ElementAtOrDefault Operator with an Invalid Index
<source lang="csharp"> using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class Employee {
public int id; public string firstName; public string lastName; public static ArrayList GetEmployeesArrayList() { ArrayList al = new ArrayList(); al.Add(new Employee { id = 1, firstName = "J", lastName = "R" }); al.Add(new Employee { id = 2, firstName = "W", lastName = "G" }); al.Add(new Employee { id = 3, firstName = "A", lastName = "H" }); al.Add(new Employee { id = 4, firstName = "D", lastName = "L" }); al.Add(new Employee { id = 101, firstName = "K", lastName = "F" }); return (al); } public static Employee[] GetEmployeesArray() { return ((Employee[])GetEmployeesArrayList().ToArray(typeof(Employee))); }
} public class MainClass {
public static void Main() { Employee emp = Employee.GetEmployeesArray().ElementAtOrDefault(5); Console.WriteLine(emp == null ? "NULL" : string.Format("{0} {1}", emp.firstName, emp.lastName)); }
}
</source>
ElementAtOrDefault Operator with a Valid Index
<source lang="csharp"> using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class Employee {
public int id; public string firstName; public string lastName; public static ArrayList GetEmployeesArrayList() { ArrayList al = new ArrayList(); al.Add(new Employee { id = 1, firstName = "J", lastName = "R" }); al.Add(new Employee { id = 2, firstName = "W", lastName = "G" }); al.Add(new Employee { id = 3, firstName = "A", lastName = "H" }); al.Add(new Employee { id = 4, firstName = "D", lastName = "L" }); al.Add(new Employee { id = 101, firstName = "K", lastName = "F" }); return (al); } public static Employee[] GetEmployeesArray() { return ((Employee[])GetEmployeesArrayList().ToArray(typeof(Employee))); }
} public class MainClass {
public static void Main() { Employee emp = Employee.GetEmployeesArray().ElementAtOrDefault(3); Console.WriteLine(emp == null ? "NULL" :string.Format("{0} {1}", emp.firstName, emp.lastName)); }
}
</source>
use ElementAtOrDefault
<source lang="csharp"> 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); }
}
</source>