Wie verwende ich Indexer in C# 8.0?

^ Operator − Vom Ende her wird er als Indexierungsoperator bezeichnet.

Es gibt den Index relativ zum Ende der Sequenz oder des Satzes zurück.

Im Vergleich zur vorherigen Methode ist dies die prägnanteste und einfachste Möglichkeit, das letzte Element zu finden.

methoden.

company.listEmployees[^2].Name = „Name von Mitarbeiter 2 mit neuer Syntax geändert“;

company.listEmployees[^5].Name = „Name von Mitarbeiter 5 mit neuer Syntax geändert“;

Unternehmen. listEmployees[^8].Name = „Namen von Mitarbeiter 8 mit neuer Syntax geändert“;

Beispiel

public class Employee{
   public int EmployeeId { get; set; }
   public string Name { get; set; }
   public string Gender { get; set; }
}
public class Company{
   public List<Employee> listEmployees;
   public Company(){
      listEmployees = new List<Employee>();
      listEmployees.Add(new Employee
      { EmployeeId = 1, Name = "SS", Gender = "Male" });
      listEmployees.Add(new Employee
      { EmployeeId = 2, Name = "SSS", Gender = "Female" });
      listEmployees.Add(new Employee
      { EmployeeId = 3, Name = "SSSS", Gender = "Male" });
      listEmployees.Add(new Employee
      { EmployeeId = 4, Name = "EE", Gender = "Female" });
      listEmployees.Add(new Employee
      { EmployeeId = 5, Name = "EEEE", Gender = "Female" });
      listEmployees.Add(new Employee
      { EmployeeId = 6, Name = "TTT", Gender = "Male" });
      listEmployees.Add(new Employee
      { EmployeeId = 7, Name = "FFF", Gender = "Male" });
      listEmployees.Add(new Employee
      { EmployeeId = 8, Name = "GGG", Gender = "Male" });
   }
   public string this[int employeeId]{
      get{
         return listEmployees.
         FirstOrDefault(x => x.EmployeeId == employeeId).Name;
      }
      set{
         listEmployees.
         FirstOrDefault(x => x.EmployeeId == employeeId).Name = value;
      }
   }
}
class Program{
   public static void Main(){
      Company company = new Company();
      Console.WriteLine("Name of Employee with Id = 2: " + company[2]);
      Console.WriteLine("Name of Employee with Id = 5: " + company[5]);
      Console.WriteLine("Name of Employee with Id = 8: " + company[8]);
      System.Console.WriteLine();
      Console.WriteLine("Changing names of employees with Id = 2,5,8");
      company[2] = "Employee 2 Name Changed";
      company[5] = "Employee 5 Name Changed";
      company[8] = "Employee 8 Name Changed";
      System.Console.WriteLine();
      Console.WriteLine("Name of Employee with Id = 2: " + company[2]);
      Console.WriteLine("Name of Employee with Id = 5: " + company[5]);
      Console.WriteLine("Name of Employee with Id = 8: " + company[8]);
      company.listEmployees[^2].Name = "Employee 2 Name Changed using new
      Syntax";
      company.listEmployees[^5].Name = "Employee 5 Name Changed using new
      Syntax";
      company.listEmployees[^8].Name = "Employee 8 Name Changed using new
      Syntax";
      System.Console.WriteLine();
      Console.WriteLine("Name of Employee with Id = 2: " +
      company.listEmployees[^2].Name);
      Console.WriteLine("Name of Employee with Id = 5: " +
      company.listEmployees[^5].Name);
      Console.WriteLine("Name of Employee with Id = 8: " +
      company.listEmployees[^8].Name);
      Console.ReadLine();
   }
}

Ausgabe

Name of Employee with Id = 2: SSS
Name of Employee with Id = 5: EEEE
Name of Employee with Id = 8: GGG
Changing names of employees with Id = 2,5,8
Name of Employee with Id = 2: Employee 2 Name Changed
Name of Employee with Id = 5: Employee 5 Name Changed
Name of Employee with Id = 8: Employee 8 Name Changed
Name of Employee with Id = 2: Employee 2 Name Changed using new Syntax
Name of Employee with Id = 5: Employee 5 Name Changed using new Syntax
Name of Employee with Id = 8: Employee 8 Name Changed using new Syntax

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