Indexer with Dictionary

Question

I am not able to proceed with the below code . Can anyone please help ?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Demo_Inidexers
{
    public class MyIndexer
    {
        Dictionary <int,string >  testdctnry = new Dictionary<int,string>()  ;
        public string this[int index,string val ]
        {
            get 
            {
                string temp;
                if (index > 0)
                    MessageBox .Show ("Hey m Zero");
                return testdctnry[index];
            }
            set
            {
                if (index > 1)
                    MessageBox.Show("Setting up");
                testdctnry.Add(index, val);
            }
        }
    }
    static class Program
    {

        static void Main()
        {
            MyIndexer MI = new MyIndexer();

        }
    }
}

In the above code how can i use both indexer and dictionary . I am very new to c# , please help . i want to understand indexer .

Answer 1

The value for setting an indexer shouldn't be used as the second argument. The get simply has no access to a set value, as there is none. In the set method there is a contextual keyword, value, that has the value set to the indexer:

public class MyIndexer
{
    private Dictionary <int,string> testdctnry = new Dictionary<int,string>();
    public string this[int index]
    {
        get 
        {
            if (index > 0)
                MessageBox.Show("Hey m Zero");
            return testdctnry[index];
        }
        set
        {
            if (index > 1)
                MessageBox.Show("Setting up");
            testdctnry[index] = value;
        }
    }
}

Answer 2

What problem are you having?

You call indexers by calling obj[args]. To use the getter, you use obj[args] as if it were a value. To use the setter, you use obj[args] on the left side of an assignment.

http://msdn.microsoft.com/en-us/library/6x16t2tx.aspx