Array - AsReadOnly

Returns a read-only wrapper for the specified array.

public static void Main()
{
    String[] myArr = { "The", "quick", "brown", "fox" };

    Console.WriteLine("The string array initially contains the following values:");
    PrintIndexAndValues(myArr);

    // Create a read-only IList wrapper around the array.
	// C# Extension Method: Array - AsReadOnly
    IList<String> myList = myArr.AsReadOnly();

    Console.WriteLine("The read-only IList contains the following values:");
    PrintIndexAndValues(myList);

    try
    {
        myList[3] = "CAT";
    }
    catch (NotSupportedException e)
    {
        Console.WriteLine("{0} - {1}", e.GetType(), e.Message);
        Console.WriteLine();
    }

    myArr[2] = "RED";

    Console.WriteLine("After changing the third element, the string array contains the following values:");
    PrintIndexAndValues(myArr);

    Console.WriteLine("After changing the third element, the read-only IList contains the following values:");
    PrintIndexAndValues(myList);

}

public static void PrintIndexAndValues(String[] myArr)
{
    for (int i = 0; i < myArr.Length; i++)
    {
        Console.WriteLine("   [{0}] : {1}", i, myArr[i]);
    }
    Console.WriteLine();
}

public static void PrintIndexAndValues(IList<String> myList)
{
    for (int i = 0; i < myList.Count; i++)
    {
        Console.WriteLine("   [{0}] : {1}", i, myList[i]);
    }
    Console.WriteLine();
}

View Source

using System;
using System.Collections.ObjectModel;

public static partial class Extensions
{
    /// <summary>
    ///     A T[] extension method that converts an array to a read only.
    /// </summary>
    /// <typeparam name="T">Generic type parameter.</typeparam>
    /// <param name="array">The array to act on.</param>
    /// <returns>A list of.</returns>
    public static ReadOnlyCollection<T> AsReadOnly<T>(this T[] array)
    {
        return Array.AsReadOnly(array);
    }
}