如何在C#8.0中使用索引器？
^运算符-最终运算符将其称为索引。
它返回相对于序列或集合结尾的索引。
与早期方法相比，这是找到末端元素的最紧凑，最简单的方法。
company.listEmployees[^2].Name=“使用新语法更改的员工2名称”;
company.listEmployees[^5].Name=“使用新语法更改的员工5名称”;
company.listEmployees[^8].Name=“使用新语法更改的员工8名称”;
示例
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();
}
}输出结果
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