Indexer to append

In this chapter you will learn:

  1. How to add value with an indexer

Add value with indexer

Indexer can both output value and input value. The following code uses indexer to add element.

using System;/*from  j a  va 2  s .  co m*/
using System.Collections;

public class MainClass
{
  public static void Main()
  {
    EmployeeList empList = new EmployeeList();
  
    empList[0] = new Employee("F");
    empList[1] = new Employee("C");
    empList[2] = new Employee("Z");

    for(int i = 0; i < empList.GetNumberOfEmployeeList(); i++)
    {
      Console.WriteLine("Employee number {0}:", i);
      Console.WriteLine("Name: {0}", empList[i].Name);
    }

    try
    {
      Console.WriteLine("Using IEnumerable");
      foreach (Employee c in empList)
      {
        Console.WriteLine("Name: {0}", c.Name);
      }
    }
    catch{}      
  }
}
public class EmployeeList : IEnumerable
{
  private ArrayList carArray;

  public EmployeeList()
  {
    carArray = new ArrayList();
  }

  // The indexer.
  public Employee this[int pos]
  {
    get
    {
      if(pos < 0)
        throw new IndexOutOfRangeException("Hey! Index out of range");
      else
        return (Employee)carArray[pos];
    }
    set
    {
      carArray.Insert(pos, value);
    }
  }

  public int GetNumberOfEmployeeList()
  {
    return carArray.Count;
  }

  public IEnumerator GetEnumerator()
  {
    return carArray.GetEnumerator();
  }
}
public class Employee
{
  public Employee(string name)
  {
    this.Name = name;
  }
  public string Name;
}

The code above generates the following result.

Next chapter...

What you will learn in the next chapter:

  1. How to write more complex code for indexer
  2. Indexer based on 0 or non-zero
  3. Use an indexer to create a fail-soft array
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