Indexer in C#

Indexers allow instances of a class or struct to be indexed just like arrays. Indexers resemble properties except that their accessors take parameters.
In the following example, a generic class is defined and provided with simple get and set accessor methods as a means of assigning and retrieving values. The Program class creates an instance of this class for storing strings.



class SampleCollection<T>
{
    // Declare an array to store the data elements.
    private T[] arr = new T[100];
    // Define the indexer, which will allow client code
    // to use [] notation on the class instance itself.
    // (See line 2 of code in Main below.)       
    public T this[int i]
    {
        get
        {
            // This indexer is very simple, and just returns or sets
            // the corresponding element from the internal array.
            return arr[i];
        }
        set
        {
            arr[i] = value;
        }
    }
}
// This class shows how client code uses the indexer.
class Program
{
    static void Main(string[] args)
    {
        // Declare an instance of the SampleCollection type.
        SampleCollection<string> stringCollection = new SampleCollection<string>();
        // Use [] notation on the type.
        stringCollection[0] = "My Name is Psingh";
        System.Console.WriteLine(stringCollection[0]);
    }
}

Output:
"My Name is Psingh"