Indexing with an String Indexer : Indexer « Class « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Class
3. Indexer

using System;
using System.Collections;
class Pair
{
    public Pair(string name, object data)
    {
        this.name = name;
        this.data = data;
    }
    public string Name
    {
        get
        {
            return(name);
        }
        set
        {
            name = value;
        }
    }
    public object Data
    {
        get
        {
            return(data);
        }
        set
        {
            data = value;
        }
    }
    string    name;
    object data;
}
class PairList
{
    public PairList()
    {
        row = new ArrayList();
    }
    
    public void Load() 
    {
        /* load code here */ 
        row.Add(new Pair("Q", 5551212));
        row.Add(new Pair("A", "text"));
        row.Add(new Pair("B", 2355.23m));
    }
    
    public Pair this[int column]
    {
        get
        {
            return( (Pair) row[column - 1]);
        }
        set
        {
            row[column - 1] = value;
        }
    }
    int FindPair(string name)
    {
        for (int index = 0; index < row.Count; index++)
        {
            Pair Pair = (Pair) row[index];
            if (Pair.Name == name)
            return(index);
        }
        return(-1);
    }
    public Pair this[string name]
    {
        get
        {
            return( (Pair) this[FindPair(name)]);
        }
        set
        {
            this[FindPair(name)] = value;
        }
    }
    ArrayList    row;    
}
class Test
{
    public static void Main()
    {
        PairList row = new PairList();
        row.Load();
        Pair val = row["A"];
        Console.WriteLine("A: {0}", val.Data);
        Console.WriteLine("B: {0}", row["B"].Data);
        row["Q"].Data = "new value";    // set the name
        Console.WriteLine("Q: {0}", row["Q"].Data);
    }
}

A: 5551212
B: text

Unhandled Exception: System.ArgumentOutOfRangeException: Index was out of range. Must be non-negativ
e and less than the size of the collection.
Parameter name: index
   at System.Collections.ArrayList.get_Item(Int32 index)
   at PairList.get_Item(Int32 column)
   at Test.Main()